I was getting 14.8 MPG so I put in some injector cleaner in my last tank of gas and only got 13.5. I never get much more than 200 miles out of a tank of gas, is there any way of improving this number? Last tank was 14.25 gal 93 oct and got 192 miles. ( I have no codes listed )

 

Gman, the mileage that our cars gets is very relative to how you drive them. With my car, i see a 4 mpg drop when the temps go from 50-60F in the morning to when they are 20-30F. Our cars do not like the cold weather (have too long of a "rich fuel cycle" program to them). So, that is probably part of your problem since the temps have been rather down in the range lately.

The other thing that I would ask is the last time the plugs were changed and what were the changed out with? If you are nearing 100K miles on double platinum plugs (factory plugs), then it may be time for new plugs. If someone cheaped out and install standard plugs, after about 15K miles, those plugs will be shot due to the high voltage coils in our cars. If you go down this route, make sure you get some quality platinum plugs. Do not worry about trying to get the "fancy multispark" plugs. They do nothing for our cars other than lighten your wallet.

I would also say to clean the mass air flow (MAF) sensor. A can of MAF sensor cleaner is like $5 and removing the MAF sensor takes all of about 5 minutes. The only caution I will tell you is to not spray straight down the hole to the fine metal wires. Spray in at an angle and let the fluid bounce off of the walls.

Also check the hose running from the PCV valve to the intake. If this is starting to split on you, it can cause your mileage to drop slightly.

How does your e-brake feel? Do you feel it have some resistance as soon as you start lifting or do you notice that you have a little bit that it is very easy and then you feel some resistance come in? If you feel no resistance off the bat, you may have your e-brakes dragging as you are driving the car. If you suspect this, after doing a 5 mile or so high speed run, stop the car and compare the temp of the rear rotors to the front rotors. If you e-brakes are dragging, when you get your hands near the rear rotors, you will feel lots of heat, but the front rotors will only be slightly warm. My car suffers from sticking e-brakes periodically and I can see it in my mileage.

ANother quirk that I have noticed is that if I do a bunch of "short trips" (I only drive 13 miles each way to work), my mileage will be a little lower right after then doing a long run vice just starting out on a long run following a compete refueling. The car needs some time to shift itself around if you suddenly start doing longer runs. Kinda like my short trip mileage will be higher after I have done say a 400 mile road trip than if I had spent the previous weeks just doing the short trips.

How do you leave stop lights? If you like to be sporty and whatnot and you have lots of lights, that can also drive your mileage way down.

Just a few things to think about and to take a look at.

 

I guess mine isn't so bad. I am getting 25 miles per gal consistantly. I drive 80 miles a day and it is mostly highway. If I could just get the heat to work I would be quite content.

 

Thermo, thanks for the tips I guess I'll try cleaning the MAF sensor. Shame this little engine does so bad on gas. I do only drive 7 miles to work and that's with a bunch of stop signs and lights along the way and I rarely rev above 3k. That's good and bad, bad is MPG, good is I only fill up twice a month and don't put that many miles on the car.

 

I drive 80 miles a day and in is 95% highway. I guess thats why mine does so well

 

The mileage I experience when driving short distances is significantly lower than long distances. Also, thanks for the advice on the plugs and the cold weather driving/mileage. Thanks, again.

 

Thermo says
When I enquired re main dealer servicing cost in the UK I got three prices all for annual /10K miles.
There was a small difference in alternate years but at 70K miles there was a significant jump in cost.
I enquired why and was told it was the scheduled plug change plus time/cost gaining access to the rear bank of cylinders.

So I can only assume that 70K is the recommended plug change in the UK but of course this may err on the safe ( more profit at an earlier date?)side.

 

henry, plug change out times are so relative right now. Our cars do not have a super high energy coil in them. So, you can get 100K miles out of the car no problem with no ill effects on the car. I know guys with Ford Trucks (they use a very similar coil on plug setup) and they have gone upwards of 150K miles on a set of plugs. Obviously the plugs were worn when they pulled them out, but the truck still ran and they didn't see a dramatic change in performance either with the new plugs.

As for doing the rear plugs, yes, they take a little bit more time, but we are not talking anything serious. I wish you lived closer to me. I would tell you to stop on buy and we would get you taken care of. Once you see what all is involved, you will laugh at what they want to do that job.

 

Thanks for your update. I am a low mileage , maybe 8K miles a year driver who usually drives a car until the tin worm gets it.
My old Ford Mondeo is quieter than my X Type but the rot is creaping in. It drives sweetly but I get concerns that with only simple airbags and rust I will be far less protected than my X type.
If the X type survives serious problems it may well be my last car.I certainly will not be concerned for a few years about plug life
Public transport etc is great where I live so less pressure to go to 100.
I have been doing less servicing myself in recent years. I have sorted a couple of minor problems but I guess I have more funds than in years gone by. I do plan to swop to HIDs
I bought a petrol version for long life ( the majority are now diesel in the UK). It was cheaper to buy but a lot more annual tax. £440 each year which is just about the top tax in the normal high powered cars ( all Aston Martins are £475 as are the biggest MB saloons and a few V8 Jaguars )

It is interesting to see the differences in what you folks do and we do re oil changes and brake fluid changes. So very different.

I would love to call by if I am your way across the pond.
I used to visit the US very regularly on business. My last trip via Washington was en route to Miami on CONCORDE just before the service stopped.
There were seven passenger on board for that leg- what a trip.

 

Thermo
Cost of a London ( in the suburbs) main dealer routine servicing.

£275 ( £224 at another MD )
£340 ( £340 )
Approx £100 for Mobile 1 Oil, labour £100+, goverment tax £50, Consumables! and disposal £13.99 ( each of the first three years ) and the rest is for parts ( filters etc)
These services alternate until:-
£ 500 @7years 70K miles.

I am not sure what happens if I deviate from the published schedule but I am not paying for a plug change at a projected mileage just over 30K so some " adjustment" will occur.

 

Henry, using an exchange rate of 1.6 USD to 1 british pound, a 70K mile service would cost me $800. I am sorry, but that buys a lot of my time and would cover tons of parts that I would not get at the dealership. I say if you can do it yourself, do it. Get to know your kitty. Know what makes her purr. The only thing that I would possibly say you want the dealership to do is a fluid change on the tranny which you should be able to get for around 100 pounds. The rest is doing an oil change (on, toughy there, pull a plug, let the oil drain, put the plug back in, spin off the filter, put the new on on, dump in 6 liters of oil). You should be able to get all that for around 30 pounds. Much less than the 100 that they are quoting you.

As for the "adjustment" at 30K miles, you can get the same effect by simply pulling the negative battery cable off, let the car sit for like 5 minutes and then put the negative battery cable back on. This clears the ECU memory and forces it to relearn your car. I tend to do this every oil change (4K miles for me), just to keep the computer with the latest information.

 

Thermo
I thought you would be interested in the numbers.
Of course given a chance they will add in washer fluid or a wiper blade but they would be warned, before they started not to try that.

I certainly would get the autobox ATF changed but would take it to a long established company that just does auto boxes. They partially rebuilt my Ford Mondeo box. I understand that the best way to change the oil is to hook it up to a sort of dyalisis machine and then do it.
Megaflush Automatic Transmission Dialysis
This is one company that I like the "sound" of.
The comentary appears to be by a hands on man not a smooth sales type. A bonus is that I visit Cambridge, near where they are based, several times a year.
Maybe start a new thread obout the task?

I do not think many folks are aware of this way of doing the job properly
Your comments and experience on the task would be appreciated.

 

Henry, the process that I think is most worthwhile that i have heard about is the process by which you first empty as much as you can out of the auto box. From there, you fill it back up and then remove the line going to the tranny cooler. You start the engine to force the fluid out there. What you will see is the darker fluid come out at first and then the fluid suddenly changing to the bright pink fluid after a few liters has been pushed out. From there, you top off the tranny and you are good. The amount of fluid that has been swapped out is nearly 100%. Granted, your place sounds like they are using something very similar to swap out good and old fluid.

 

Just for the books, I had terrible gas mileage (around 16mpg) and couldn't figure it out. Then I changed my plugs, plenum gasket, booster hose, pcv hose (2004+ hose,) and imt o-rings and now I'm back up to around 18-20mpg in the same conditions. That's just what did it for me.

 

Gman, if you don't mind a little bit of a drive (about 200 miles each way), I would tell you to come on down and we can get you taken care of in an afternoon. Doing the plugs is easy. If you are in there, probably worth your while to spend the extra $20 to get new "intake plenum gaskets (made by Felpro)" to ensure you don't have a vacuum leak later. You can do the lower intake gaskets, upper intake gaskets, and plugs all in about 3 hours if you take your time. If you have done it before, then you can probably do it in 2-2.5 hours.

 

Thermo, I may take you up on that in the summer just to take it for a good ride. My last car, a 2001 taurus 3.0 that I put 140k on before I got this car. I changed the plugs at 100K and to be honest they looked pretty good. The car right now has 66K on it and I have only put 1k on it in the 4 months I've owned it.

 

Just came back from LA and here are some interesting observations:

SF-LA cruising mostly at 85-90 mph gave me ~ 22mpg.

In LA I replaced the fuel filter (it had been changed ~35k miles ago) and...nothing actually changed. Driving on the PCH (Hwy1) around Malibu with 4.5-6k revs, gave me 21mpg, and then cruising at ~75mph gave me 22mpg.

The spark plugs were changed ~20k miles ago. The air and fuel filters are new. Gasoline Premium. Gearbox - manual.

In the past, same route gave me ~ 27mpg cruising at 78-80mph.
My guess is that putting extremely sticky Michelin Pilot Super Sports affected fuel economy a little.

 

Has the California fuel mix changed lately? More ethanol less mpg... :-(
================================================
Jaguar - it's not an automobile, it's a Motorcar

 

Aack! ETHANOL?

Stay well away from the blended ethanol/gas fuel, look for a station that sells a NON-ETHANOL premium fuel.

An ethanol blend, or non-premium fuels will both affect your mileage AND performance adversely.

Ethanol has the extra, added property of being "hydroscopic"; it absorbs just about it's own weight in WATER right out of the air. By the time you pump it into your tank, the fuel is packed pretty full of water.

If you look in your Jaguar Operator's Manual, you will read that ethanol blends are NOT recommended, nor is any fuel but a Premium Grade.

 

pab, depending on where you live, they will alter the times that the summer and winter blends of gas are used. The winter blend has chemicals added that help saturate the gas with oxygen, helping it burn cleaner in the cold weather. BUt, as a side effect, the mileage of your car will drop.