Recent content by Ultrasonic

Thanks. You probably posted it elsewhere but it's not in this thread. Guess the aerodynamic effect is the dominant one? US miles are exactly the same distance as UK miles by the way, it's gallons that are different which makes mpg figures different.

Thanks for the updates. Out of interest, what is your typical driving like in terms of trip length, city/highway and speed? Just thinking in terms of what your data shows, since presumably short trips and city driving will be more affected by longer warm up times at lower temperatures, whereas...

Interesting data from SkeeterMark. I note that the MFD appears very accurate for the first few tanks and then got worse but I can't think of any sensible explanation for this? Yes you'd expect fuel economy to improve a little as the engine wears in, but why would this make the MFD mpg less...

LOL! Excellent use of a crash photo :D. I think I'm right in saying that the most effective aero-mods used to be grill blocks, which would probably be pretty complicated to model with CFD code since you'd need much of engine bay geometry? But I guess on modern cars the front grills have already...

That drop in mpg with the grill blocks removed is certainly larger than you'd expect to be caused by a 5°F drop in temperature. I've considered making some grill blocks for my car but have never got round to it.

It's interesting how high those idle fuel consumption figures are actually; I assume that's fully warmed up? My older 1.9 TDi has idle fuel consumption of about 0.16 gph (and I have converted that to US gallons), according to my ScangaugeII.

The fuel use at idle will be the same whatever the speed of the car. But what is probably more relevant is the mpg whilst coasting in neutral, and your trip computer will show that (albeit probably a bit optimistically). I assume on a 2013 car you must have a trip computer, right? It might help...

The temperature difference will likely be contributing to the higher mpg you've seen, how much will depend on how large the temperature difference was. I'm not saying your AFE kit didn't improve mpg, just that temperature may not be an irrelevant factor, and it is frustratingly very difficult to...

Did you read what I wrote below the link to Vekke's thread :confused:. If you haven't already, do have a read of Vekke's thread and watch some of his videos.

That's somewhat debatable: http://forums.tdiclub.com/showthread.php?t=335035 I believe that accelerating slowly 'works' where it helps drivers to avoid unnecessary acceleration, but if you can learn to read the road ahead then you can improve mpg without your accelerator pedal wondering if...

The trip computer in my 2005 VAG car gives mpg figures that are 25% optimistic. This is probably an extreme example, but they certainly can be off. If you haven't checked your 59 mpg figure then I stongly suspect you were getting rather lower than that. It is certainly possible that the chip you...

I hadn't thought of it in those terms before. My car's indicated mpg is about 19% optimistic: I'd always assumed it was an incorrect calibration rather than a dodgy sensor that is the cause. But I guess you're right it could also be caused by a sensor fault.

Your 59 mpg figure does sound very good. What speed highway driving are we talking about? I assume this is an mpg figure that you've checked, rather than it just coming from the car trip computer?

Are you sure you wouldn't get better fuel economy in 5th? I don't know how your car is geared, but I'd be surprised if you didn't get better fuel economy in 5th at those speeds.

That sort of variation is in line with what others are talking about I'd have thought? The air resistance effect will be most noticeable for long highway drives, and more so at higher speeds, so your driving pattern may be a factor here. Nobody is claiming the air density factor is the only...