VMW, just curious: you mentioned by disabling the DSC gives a small increase in fuel economy. I don't know much about the technical details of it, but doesn't that work by sensing wheel slip and then intervening? If so, unless it would detect a reason to intervene, doesn't it just "sit there"? If that is the case, why would disabling that increase the fuel economy? Also, when you say a small increase how much are ytou talking about? And how did you measure that gain?

What kind of tires are you running on your S Type? 80K miles is quite a feat. I know the roads and weatehr in California are a lot less punishing than here in Wisconsin, but 80K IS exceptional.

I see you mention removing the passenger mirror for reduced drag. I can certainly see that (and less wind noise), but isn't that a little dangerous? Is that even legal?

 

I don't know about the laws there, but here, you only have to have both side mirrors if you do not have a windsheild mount rear view, or its view is obstructed. Years ago, I owned an 86' Mercury Lynx (Ford Escort) that came factory without the passenger side mirror.

 

C5pilot, I seem to have steered this thread in the wrong direction. I was miffed at your curt response to my post and took it as a personal attack. I responded in kind and angered you in return. You are knowledgeable and an accomplished racer and are justifiably proud of your achievements ( as I am of mine ).But your expertise in drag racing does not diminish my knowledge in the arena of fuel economy. Our respective disciplines have different goals and need different compromises to achieve optimal results. I apologize to you for my attack and hope that we can engage in a civil discussion on the topic of fuel economy.

I hoped to expose our members to additional fuel economy techniques beyond the usual recommendations ( drive slower, moderate acceleration, clean out your trunk, etc. ) and
share some of my personal experiences and opinions. You are correct that higher tire pressure makes the suspension work harder on bumpy surfaces and the ride harsher but I haven't found it to display unsafe handling, braking or excessive tire wear. Rather than argue can we agree that inflating the tires to the manufacturer's maximum pressures delivers more fuel economy than lower pressures?

In my enthusiasm I sometimes forget how controversial some hypermiling techniques are viewed. Some such as close drafting and engine-off coasting are dangerous and not appropriate for public streets. I agree with you that safety must come first.
Thanks for listening, VMV

 

Hi,
Alfadude, my theory on why shutting off the DSC returns higher mpg is that it reduces rolling friction which it manages through applying the brakes. The effect is small but observable during steady state cruising and turning it on and off. Not recommended during rain or other diminished traction situations.

Removing the R side mirror resulted in about a .2 mpg improvement. Here in CA you are required to only to have a L side mirror and a interior rear view mirror. During my experiment I used a temprorary interior R side mirror . I put the mirror back on as the benifit was small, it was ugly and it made backing my car into its single car garage a hassle.
best wishes, VMV

 

I would agree that there would be some resitance if the DSC was activated, but wouldn't that only happen if it sensed a wheel losing traction and only for a very brief instant? If I am thinking correct wouldn't that be next to nothing saved in gas mileage unless it was on all the time for a long stretch of road, in which case it would probably be a good idea to have it on as the road conditions would be really bad? If I am misunderstanding how that would work let me know. Just trying to understand. How would you even measure that?

 

Alfadude, The fuel economy improvement may come from either the electrical draw from activating the system ( like running your headlights) or from some increased rolling resistance ( either very slight brake drag or field resistance). I don't know for sure and its an excellent question that I'll try to research. As far as quantifying how large an effect, testing it with a Scangauge or similar device with DSC on and then off on identical courses would be the best way. Other than that one could use the mpg function of the trip computer on a short run with DSC on, say 5-10 miles, reset , then repeat the same course with it off.
My tires are the original Bridgestone Turanzas, now with 90K miles on them.
best wishes VMV

 

I thought you already had tried it and measured a difference. If you are drawing more electricity to run something, yeah, I could see it having an effect on mpg. But the amount needed to just have the system activated I would think would be extremely small and the difference in mpg would be so small that it would not be measureable by the readout on the dash. To me this sounds like something so small that it would be all but impossible for someone to quantify without having all kinds of expensive elctronic gear under the strictest of conditions. If you would save .0002 gallons of gas every couple years by doing this it doesn't seem worth it. In every day use it just doesn't seem practical to me. Granted, I am basing this on nothing other than it doesn't pass my own internal smell test radar and I could be wrong. I will trade the peace of mind knowing the DSC is on (even in good weather you might need it in a split second).

If you could find anything quantifying the actual effect that would have I would be interested out of curiousity.

 

I wasn't attempting to diminish your knowledge of fuel economy. I was trying to point out that your goals are almost entirely at the expense of safety (and mush less importantly, performance). Advising people to drive at steady reasonable rates is one thing. Advising people to remove mirrors, tailgate traffic, over inflate tires and turn off their engine while driving, etc... You're piling on a lot of things that diminish safety and quite frankly for very modest returns.

That may be acceptable on a hypermiling forum where most understand the risks but this is a Jaguar enthusiast forum. I'd never say we don't care about mpg but there is a line where the end results don't justify the means. It's difficult to say what other people would consider an acceptable gain at the expense of even a little safety.

I didn't mention before that I also hold a commercial drivers license and a pilots license, both of which required extensive training and centered on the principle of, "safety first". That said, I'm no angel, and don't want to come off like a hypocrite. I've done my share of stupid things and continue to do so. But I'd never publish a paper on what I gained from pulling some dangerous stunts.

There's an old saying in aviation, "There's nothing less useful than the runway behind you and the sky above you". Meaning, don't let any safety precautions go to waste just because you've never needed them before. I've had the distinct "pleasure" of experiencing a low altitude engine failure. It's not something I'd ever thought I'd experience, yet I practiced emergency landing procedures everyday during training. At one point, almost 20 years had passed since I had regular formal training. I'll tell you what, maybe my brains are in my *ss because when my sphincter tightened up at the sound of the engine dying, all those emergency procedures came back in an instant.

All I'm trying to say is, in an emergency, all the things you're doing to save minuscule amounts of gas could cost you your life or someone else's. It won't matter one iota that you wouldn't be dead if "that idiot" you were drafting didn't slam on his brakes, causing you to brake hard and swerve on over-inflated tires into the next lane where you didn't see the car beside you because you had no mirror. Everything adds up real fast in an emergency.

Lastly, I didn't consider what you said "an attack", we're having a discussion. I tend to type as if we're speaking face to face which probably comes across a little more coarse than it should (I apologize for that in kind). The only thing I took personally was the request for my credentials which shouldn't have any bearing on the topic of safety vs mpg.

Agreed. You could save even further electrical draw by disconnecting all the lights and air bags too! Electrical draw adds up to nothing measurable. Alternator drag is nothing like the A/C compressor which has measurable losses when it's engaged.

 

One factor is whether your gas contains ethanol. This will reduce the MPG on average by 2-3 MPG. Hey, we love ethanol here in Iowa but it is kind of crappy, fuel mileage wise.

 

I checked the other day, and I average 16 MPH and get 16.2 miles per gallon. However, I work from home, rarely leave town, and use my X Type mostly for running my kid around town.

 

Guys, got an x-type 2.5SE 2007 don't drive too much in but on a 60 mile run today got 30mpg on a 300 mile run last week got 34mpg at 70mph - car has 7800 miles. hope this helps

 

Lol i get gallons per mile(useally about 3gal/mile) out of my 580 cubic inch engine in my 79 el camino. 8-9 seconds at a time
Thats a pic in my avatar

 

Just took a nice 300 mile trip in the X-type. Very comfy and averaged about 28.5 MPG for entire trip, all highway driving at 65-70 MPH.

Not bad.

 

Hi all

I'm new here and have found this thread quite interesting, I've just bought a 2003 2.1 x-type SE.
This seem a smaller engine than had previously been mentioned in this thread. My mpg is currently showing as 18.5. I don't drive to aggressivly and I'd always round town.
From what I've gleened from here I'd say I'm a little below par mpg wise and would be very appriciative of any input or help given. Would changing the air filter help at all, please excuse my ignorance as this is my first car so a total newbie at all this

 

What type of oil are you using?
my dad would run 20/50 in the summer on his trucks and 10/40 in the winder. yes, yikes!
and then at the dinner table the wallet would moan and groan because of its empty internals

 

Have an 04 X 2.5 w/ 100k on it and get 20-22 in town and about 24-25 hwy.
And I baby the accelerator to get that. Also have found that different gas stations yield different results, costco causes miss at idle and hesitation but best mileage. The other stations shell and mobil no miss or hesitation and a 18-20 mpg count.Also maintain tire pressure. One last thing I'm in FL, no hills, which may slightly improve mpg.

 

Is this pissing contest over now....???

Geeze,

 

i do a lot of mixed driving and mine is typically between 23-24 MPG. I'd say i drive fairly conservative (I like to "cruise" in my Jag)