Crummy Gas Mileage
#41
12-24-2010, 02:24 PM
#42
12-25-2010, 03:55 AM
Addendum to "factors influencing mpg".
It's easy to forget the principle behind having a good mpg figure from your car. And that principle is SAVING MONEY. So there is another principle behind the principle, as 'twere.
The Toyota Prius is a classic. If you drive it appropriately, it WILL produce a good mpg figure, even though it's a petrol car. But what do you have to spend to achieve this? An awful lot of money is the answer! To start with, the car is far more expensive than it's non-hybrid competitors. You'd have to use it from now 'til Doomsday to recoup the losses in original purchase. And something they don't tell you... That nice lithium-ion battery has a limited life of only so many charges (I believe it's around 400 cycles) and it's expensive, half the original cost of the car. Meaning after around 8 years or so, the car becomes an economic write-off. It's value becomes near zero. These are basic economics that won't go away. Many years ago, diesel versions of petrol cars were considerably more to buy new. Unless you did a high mileage then, diesel was false economy. Nowadays, the situation is reversed. Diesels are near enough the same to buy new. I can say with certainty that residual values of diesels are higher than the equiv. petrol version, and will sell more readily in UK. All the old criticisms of diesels have gone, they don't smell, they aren't partic. noisy, they start easily, and the specific power and torque make them better for normal use than petrol. The only factor remaining is the pump-price of the fuel, where in UK diesel is slightly more than petrol -- it used to be less than half back in the 1960s.
Diesel cars in the US:--
Where petrol is cheap, cars tend to be big and thirsty, most drivers liking a quiet and comfortable car. Fuel consumption is not a big issue. I remember with envy the US price of petrol in the 1960s was around 22cents a gallonUS. I understand now it's around $4 per gallon in some places. The number of postings right here indicates a big US interest nowadays in fuel consumption -- so I can say with certainty more and more diesel cars will in the future be sold in US as buyers realize the economics DO add up.
To close this, might I say...
"Economy is no good if you have to pay for it".
Leedsman.
It's easy to forget the principle behind having a good mpg figure from your car. And that principle is SAVING MONEY. So there is another principle behind the principle, as 'twere.
The Toyota Prius is a classic. If you drive it appropriately, it WILL produce a good mpg figure, even though it's a petrol car. But what do you have to spend to achieve this? An awful lot of money is the answer! To start with, the car is far more expensive than it's non-hybrid competitors. You'd have to use it from now 'til Doomsday to recoup the losses in original purchase. And something they don't tell you... That nice lithium-ion battery has a limited life of only so many charges (I believe it's around 400 cycles) and it's expensive, half the original cost of the car. Meaning after around 8 years or so, the car becomes an economic write-off. It's value becomes near zero. These are basic economics that won't go away. Many years ago, diesel versions of petrol cars were considerably more to buy new. Unless you did a high mileage then, diesel was false economy. Nowadays, the situation is reversed. Diesels are near enough the same to buy new. I can say with certainty that residual values of diesels are higher than the equiv. petrol version, and will sell more readily in UK. All the old criticisms of diesels have gone, they don't smell, they aren't partic. noisy, they start easily, and the specific power and torque make them better for normal use than petrol. The only factor remaining is the pump-price of the fuel, where in UK diesel is slightly more than petrol -- it used to be less than half back in the 1960s.
Diesel cars in the US:--
Where petrol is cheap, cars tend to be big and thirsty, most drivers liking a quiet and comfortable car. Fuel consumption is not a big issue. I remember with envy the US price of petrol in the 1960s was around 22cents a gallonUS. I understand now it's around $4 per gallon in some places. The number of postings right here indicates a big US interest nowadays in fuel consumption -- so I can say with certainty more and more diesel cars will in the future be sold in US as buyers realize the economics DO add up.
To close this, might I say...
"Economy is no good if you have to pay for it".
Leedsman.
#43
12-25-2010, 07:54 AM
Veteran Member
GM is probably more responsible for the lack of a passenger car diesel market in the US than any "cheap" petrol prices. They launched the "Oldsmobile Diesel" in the late 70's, which left a sour aftertaste that lingers still. The full-size pickup market diesels have made ammends to an extent, but I believe people are still suspicious of the concept.
#44
12-25-2010, 08:35 AM
Veteran Member
#45
12-25-2010, 08:43 AM
Veteran Member
I get like 280 miles out of a tank... It is what it is really. These claims of 30+ mpg have me amazed. These guys driving 45 degrees downhill both ways or something? Do they get the car to 70 never exceeding 2000 rpm, set the cruise and putt along in the right lane and don't ever touch the brakes till they get where they are going?
I agree the whole ethanol / E85 programs are vast wastes of resources, but the government is so behind... Billions in farm subsidies have been given to basically cut gas with grain alcohol and reduce it's energy content, while people are allowed to starve and the price of food has doubled.
I also don't agree that at least in Jersey, with our 15% "MTBE" winter blend, that we really do anything to help the environment. E85 (85% ethanol, 15% gas) has an octane rating of about 105. It burns a lot quicker / hotter than gasoline. BUT it has a lot less stored energy - roughly 75% of the BTU value, so it requires a 30-40% greater volume of fuel to make the same power. The only thing it really does is help the engine get to operating temp quicker, theoretically getting out of closed loop faster and speeding up operation of the cats... It's one thing to have these new "flex fuel" cars that are designed to run on E85, which I have only seen at a couple pumps in Jersey, and another thing to cut gas with alcohol.
I know a lot of the race guys make "race fuel" by mixing E85 and regular 87 octane gas. In equal parts it gives you about a 100 octane mixture, which is great for preventing detonation (and lean conditions), and only about 15% lower energy storage (which can be compensated for in tuning). Once again, this is an arena for high compression, or forced induction engines that do not run well on 93 octane premium (or you have to take timing out of to avoid pinging). I haven't tried this on my drag car, (which is at 14:1 and struggles to start, and idle) but I was thinking about it next season. Usually spraying brake cleaner into the carb will get it to fire, and you have to dual pedal it on the street to keep it idling. I'd have to bump the carb's jets up a couple sizes. But no big deal there.
The biggest problem with Ethanol in fuels, especially primarly ethanol based fuels is their tendency to attack steel and especially rubber fuel lines. Basically the entire fuel system has to be stainless steel to avoid problems in the long run.
George
I agree the whole ethanol / E85 programs are vast wastes of resources, but the government is so behind... Billions in farm subsidies have been given to basically cut gas with grain alcohol and reduce it's energy content, while people are allowed to starve and the price of food has doubled.
I also don't agree that at least in Jersey, with our 15% "MTBE" winter blend, that we really do anything to help the environment. E85 (85% ethanol, 15% gas) has an octane rating of about 105. It burns a lot quicker / hotter than gasoline. BUT it has a lot less stored energy - roughly 75% of the BTU value, so it requires a 30-40% greater volume of fuel to make the same power. The only thing it really does is help the engine get to operating temp quicker, theoretically getting out of closed loop faster and speeding up operation of the cats... It's one thing to have these new "flex fuel" cars that are designed to run on E85, which I have only seen at a couple pumps in Jersey, and another thing to cut gas with alcohol.
I know a lot of the race guys make "race fuel" by mixing E85 and regular 87 octane gas. In equal parts it gives you about a 100 octane mixture, which is great for preventing detonation (and lean conditions), and only about 15% lower energy storage (which can be compensated for in tuning). Once again, this is an arena for high compression, or forced induction engines that do not run well on 93 octane premium (or you have to take timing out of to avoid pinging). I haven't tried this on my drag car, (which is at 14:1 and struggles to start, and idle) but I was thinking about it next season. Usually spraying brake cleaner into the carb will get it to fire, and you have to dual pedal it on the street to keep it idling. I'd have to bump the carb's jets up a couple sizes. But no big deal there.
The biggest problem with Ethanol in fuels, especially primarly ethanol based fuels is their tendency to attack steel and especially rubber fuel lines. Basically the entire fuel system has to be stainless steel to avoid problems in the long run.
George
Remember that the alcohol was also added nationwide as a replacement for MTBE which was creeping into the ground water and never going away. Then the AG lobby got hold of it all.
#46
12-25-2010, 08:46 AM
Veteran Member
No, not 5 mpg unless your tires are flat. I assume by oil change you mean going to a 20 weight oil or something? I don't think I'd try that one.
#47
12-25-2010, 08:57 AM
Veteran Member
more Maserati's on the program and it is all rather staged. For me the most enjoyable episode was when they all had to purchase beaters for 500 pounds or something. Then drive them 500 miles and run them around the track. He was doing fine until he insisted on running his Volvo in a concrete barrier and actually injured himself.
I liked that one. So representative of his approach.
#48
12-25-2010, 04:13 PM
Veteran Member
+1 on that. Sorry but I find Clarkson to be quite the A-hole. He's stupidly ruined
more Maserati's on the program and it is all rather staged. For me the most enjoyable episode was when they all had to purchase beaters for 500 pounds or something. Then drive them 500 miles and run them around the track. He was doing fine until he insisted on running his Volvo in a concrete barrier and actually injured himself. I liked that one. So representative of his approach.
more Maserati's on the program and it is all rather staged. For me the most enjoyable episode was when they all had to purchase beaters for 500 pounds or something. Then drive them 500 miles and run them around the track. He was doing fine until he insisted on running his Volvo in a concrete barrier and actually injured himself.
I liked that one. So representative of his approach.Never saw the one where he ran the Volvo into the barrier, but sounds like typical Clarkson.
George
#49
12-25-2010, 07:28 PM
Mileage update:
I added 5 lbs to the tire pressure to 35 psi. I noticed a definite difference in the handling characteristics. Car was a tad easier to steer and the tires transmitted more road vibrations into the cabin. That did not bother me at all.
I drove it little more gently on the return trip - Set the cruise at 78-80 mph and was able to achieve 27.6 indicated mpg. This is much more acceptable in my eyes and I am more comfortable with that result. It would have been 27.8 or even 28.0 if I had not taken a few quick blasts to 100 mph to put space around the car and did some neck snapping passes on a few 55 and 60 mph two lane blacktop on the way home.
I attribute the mileage improvement to those factors plus a warmer overall temperature. In addition, I believe that I had a bad tank of gas in the beginning part of the trip. Time will tell what is really going on.
I added 5 lbs to the tire pressure to 35 psi. I noticed a definite difference in the handling characteristics. Car was a tad easier to steer and the tires transmitted more road vibrations into the cabin. That did not bother me at all.
I drove it little more gently on the return trip - Set the cruise at 78-80 mph and was able to achieve 27.6 indicated mpg. This is much more acceptable in my eyes and I am more comfortable with that result. It would have been 27.8 or even 28.0 if I had not taken a few quick blasts to 100 mph to put space around the car and did some neck snapping passes on a few 55 and 60 mph two lane blacktop on the way home.
I attribute the mileage improvement to those factors plus a warmer overall temperature. In addition, I believe that I had a bad tank of gas in the beginning part of the trip. Time will tell what is really going on.
#50
12-25-2010, 07:37 PM
http://www.streetfire.net/video/top-...-1_2100196.htm
Wish I'd known beforehand they were filming it. I speak "Hillbilly" fluently and would've offered to ride along as translator. ....not sure they'd understand my brand of English, though...
but back to topic Leedsman makes a thorough treatment of the factors affecting fuel economy (though I'd argue if his methods outlined in 1) are employed judiciously, you'll arrive at litres/100 km -actually, Gal/mi which would be < 1 even for supercars driven briskly causing one to scratch one's head and re-figure) but I believe few on this board are interested in scrunching up behind the wheel of an econobox and gingerly pedaling around for 50-70 mpg. Rather, we seem to have S-Typer's with long histories of 20 mpg and below and others reporting 30+. Understandibly, the low-mileage guys are wondering "what's up?" Can't speak for the V-8's, though I suspect they'd be as economical as the 6's if not moreso, but from personal experience using the fill-to-fill method on 2 different 3.0L's...I see both sides. Stop and go or even a bunch of short trips that are 80% highway will keep you below 20, whereas sustained highway runs with limited stop's will push you toward 30 and beyond. My experience is that the computers are not that bad, normally trying to make you feel better by about 1 -1.5 mpg, depending upon how you handle the resets.
Wish I'd known beforehand they were filming it. I speak "Hillbilly" fluently and would've offered to ride along as translator. ....not sure they'd understand my brand of English, though...
but back to topic Leedsman makes a thorough treatment of the factors affecting fuel economy (though I'd argue if his methods outlined in 1) are employed judiciously, you'll arrive at litres/100 km -actually, Gal/mi which would be < 1 even for supercars driven briskly causing one to scratch one's head and re-figure) but I believe few on this board are interested in scrunching up behind the wheel of an econobox and gingerly pedaling around for 50-70 mpg. Rather, we seem to have S-Typer's with long histories of 20 mpg and below and others reporting 30+. Understandibly, the low-mileage guys are wondering "what's up?" Can't speak for the V-8's, though I suspect they'd be as economical as the 6's if not moreso, but from personal experience using the fill-to-fill method on 2 different 3.0L's...I see both sides. Stop and go or even a bunch of short trips that are 80% highway will keep you below 20, whereas sustained highway runs with limited stop's will push you toward 30 and beyond. My experience is that the computers are not that bad, normally trying to make you feel better by about 1 -1.5 mpg, depending upon how you handle the resets.
I am really happy that my mileage went up on this trip and was able to achieve 27.6 mpg on my trip back without having to resort to setting the cruise at 70 mph. 70 mph is simply too slow for today's cars on today's highways. It is the new 55 mph. (I cruise by the GPS, so in general, when I say 80, it means 80.)
I find that my computer is about 1-1.4 mpg optimistic. That's okay, though.
Overall, S-type Jags are the best balanced, best for the money car on the road. I'm glad that not too many people know about them. I want to acquire another one someday.
#51
12-26-2010, 03:42 AM
Tip for UK petrol buyers: Input the litres you've bought to your calculator and divide by 4.55. This result figure is gallonsUK. You can then input the miles covered and divide by the gallons. This will give you an accurate figure of mpg, limited only by the accuracy of your car's mileometer as the pump will be calibrated regularly. If your tyres are not standard for the car in terms of outside diameter, there will be a small error.
Anecdote: My last boss ran Jaguars, the XJ6 4.2litre on the house. He drove it usually as fast as it would go -- he was no slug. Almost by accident his secretary one morning revealed to me the overall mpg of the jaguar in a 12month period, as required for UK tax purposes. It was 9mpg, yes NINE mpgUK.
Leedsman.
Anecdote: My last boss ran Jaguars, the XJ6 4.2litre on the house. He drove it usually as fast as it would go -- he was no slug. Almost by accident his secretary one morning revealed to me the overall mpg of the jaguar in a 12month period, as required for UK tax purposes. It was 9mpg, yes NINE mpgUK.
Leedsman.
#52
12-26-2010, 09:19 AM
A footnote to ethanol use in petrol engines:
To do justice to ethanol, (and methanol) the petrol engine needs a much higher compression ratio than that found commonly in Jags, (around 10.5:1). It's a slow-burning, high octane fuel. The air/fuel ratio needs to be around 6 or 7:1, i.e. twice as much fuel as for petrol at around 15:1 stoichiometric for hot engine. Ethanol, a carbohydrate, is already partly loaded with oxygen (as if it had been partially burned), hence the greed for fuel when burned in a standard petrol engine. Much the same applies to methanol. Conversly, petrol is a blend of hydrocarbons having NO oxygen in the molecule.
Ethanol -- C2 H5 OH: note the oxygen already there.
It's therefore a safe conclusion that blending ethanol with petrol and using it in a conventional petrol engine without major modification will produce a WORSE fuel consumption figure than petrol alone.
If one's intent is to reduce CO2 emission from petrol engines, a far better way is to use propane and/or butane as LPG., or compressed natural gas (methane largely), as CNG.
Methane = CH4 -- i.e. no oxygen in the molecule. Propane = C3H8, so LPG's CO2 output is just over HALF that of petrol, horses for horses.
LPG as fuel already works fine in petrol engines, using a simple conversion, providing a slightly worse fuel consumption, say 15mpg. becoming 14mpg. If the compression ratio were increased to 12.5:1 and using propane alone, the power output would be noticeably better than petrol, resulting in a better fuel consumption, power for power. LPG also needs a lot less enrichment for cold running, another saving. Carbon monoxide pollution at idle is unmeasurable for LPG.
The economic factor raises it's ugly head with LPG., as the cost of installing the tank, the cost of converting a petrol engine with vaporizer, emulator to fool the EMU, etc. is not inconsiderable, between £1000 and £2000. In UK, Volvos and Vauxhalls can be had ready converted in the factory.
Leedsman.
To do justice to ethanol, (and methanol) the petrol engine needs a much higher compression ratio than that found commonly in Jags, (around 10.5:1). It's a slow-burning, high octane fuel. The air/fuel ratio needs to be around 6 or 7:1, i.e. twice as much fuel as for petrol at around 15:1 stoichiometric for hot engine. Ethanol, a carbohydrate, is already partly loaded with oxygen (as if it had been partially burned), hence the greed for fuel when burned in a standard petrol engine. Much the same applies to methanol. Conversly, petrol is a blend of hydrocarbons having NO oxygen in the molecule.
Ethanol -- C2 H5 OH: note the oxygen already there.
It's therefore a safe conclusion that blending ethanol with petrol and using it in a conventional petrol engine without major modification will produce a WORSE fuel consumption figure than petrol alone.
If one's intent is to reduce CO2 emission from petrol engines, a far better way is to use propane and/or butane as LPG., or compressed natural gas (methane largely), as CNG.
Methane = CH4 -- i.e. no oxygen in the molecule. Propane = C3H8, so LPG's CO2 output is just over HALF that of petrol, horses for horses.
LPG as fuel already works fine in petrol engines, using a simple conversion, providing a slightly worse fuel consumption, say 15mpg. becoming 14mpg. If the compression ratio were increased to 12.5:1 and using propane alone, the power output would be noticeably better than petrol, resulting in a better fuel consumption, power for power. LPG also needs a lot less enrichment for cold running, another saving. Carbon monoxide pollution at idle is unmeasurable for LPG.
The economic factor raises it's ugly head with LPG., as the cost of installing the tank, the cost of converting a petrol engine with vaporizer, emulator to fool the EMU, etc. is not inconsiderable, between £1000 and £2000. In UK, Volvos and Vauxhalls can be had ready converted in the factory.
Leedsman.
Last edited by Leedsman; 12-26-2010 at 10:29 AM. Reason: Error correction.
#53
12-27-2010, 09:14 AM
Ben I'm very interested in this at the moment. I have a 2005 STR and the best "indicated" mileage I've ever seen is way below that, even when I was being a lol on long trips. The actual mileage was even worse. Are you quoting numbers from the on-board fuel system computer? Even so my computer never displays average fuel economy numbers like that. Are you quoting the instantaneous ones or what?
BTW, open highway I will set cruise about 75MPH, if it's a 70MPH zone I'll go 80.
#54
12-28-2010, 02:57 AM
Here, in Missouri, Premium fuel (91 octane or higher) isn't required to contain any ethanol. I'm very picky about where I get my fuel, and if I see that sticker, I move on down the road. I avoid it like the plague since it sells for the same price while lowering performance.
On another note, with fuel prices as they are, I over-inflate my tires and get a better ride while saving money (and the planet - gag!). I ran the math using my van, and by running my tires 5lbs over, I still save nearly $1000 throughout the life of the tires, even though that life is shortened.
On another note, with fuel prices as they are, I over-inflate my tires and get a better ride while saving money (and the planet - gag!). I ran the math using my van, and by running my tires 5lbs over, I still save nearly $1000 throughout the life of the tires, even though that life is shortened.
#55
12-28-2010, 08:05 PM
#56
12-29-2010, 01:54 AM
Veteran Member
Those numbers were indicated - sort of. The computer seems to read 1-1.5MPG high around town compared to a fill-fill average. I never did a fill-fill calculation on my highway trips, but I did knock off 1MPG from each indicated reading. I can see 27.X MPG (as indicated!) if I'm doing straight highway driving with little traffic, so that probably means 25+. And I saw a bit over 25MPG in highway driving with heavy traffic, so 23+. Next time I do a long highway trip, I'll do some fill-fill calculations and post 'em up, but it may be awhile.
BTW, open highway I will set cruise about 75MPH, if it's a 70MPH zone I'll go 80.
BTW, open highway I will set cruise about 75MPH, if it's a 70MPH zone I'll go 80.
Bob S.
#57
12-29-2010, 08:22 AM
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#58
12-29-2010, 08:32 AM
Veteran Member
My mom was born there. Walked 4 miles to school every morning. In the snow, uphill, both ways. That was AFTER milking the cow too ...
God I wanted so to quip "So when did you find time to have me?" But I didn't dare. See, she also was in charge of drowning the excess kittens that are invariably born on a farm. Aren't moms just great ...
God I wanted so to quip "So when did you find time to have me?" But I didn't dare. See, she also was in charge of drowning the excess kittens that are invariably born on a farm. Aren't moms just great ...
#59
12-29-2010, 09:54 AM
Veteran Member
I see those kind of numbers too. If you can sustain them long enough then you might be getting some impressive mileage. Measure it via the odometer and the gas pump then I'll listen. The on-board stuff is fantasy info. At least it is on my car. But even that never told me over any long distance that I got 26 mpg. Perhaps I drive uphill too much???
Bob S.
Bob S.
On my last fillup distance traveled v/s gallons added showed 20.07 real world mpg.
However, i only took on 12.8 or so gallons, and the car was almost indicating empty, and the range was 30 some odd miles. Don't these things hold 18.6 gallons of fuel? Wouldn't I have almost 5 gallons left? I agree that the on board stuff is indeed fantasy.
George
#60
12-29-2010, 10:19 AM
My car gets between 21.6 and 22 indicated with my driving conditions.
On my last fillup distance traveled v/s gallons added showed 20.07 real world mpg.
However, i only took on 12.8 or so gallons, and the car was almost indicating empty, and the range was 30 some odd miles. Don't these things hold 18.6 gallons of fuel? Wouldn't I have almost 5 gallons left? I agree that the on board stuff is indeed fantasy.
George
On my last fillup distance traveled v/s gallons added showed 20.07 real world mpg.
However, i only took on 12.8 or so gallons, and the car was almost indicating empty, and the range was 30 some odd miles. Don't these things hold 18.6 gallons of fuel? Wouldn't I have almost 5 gallons left? I agree that the on board stuff is indeed fantasy.
George