Accurate way to measure idling fuel consumption

[Larry1LT]

I switched from N to D many times on a 60 mile trip yesterday, I never noticed any noises or vibrations. I will try to rev match it anyway, I don't want to damage my transmission. It's a tiptronic transmission, don't know if that makes a difference.

[theholycow]

The tiptronic stuff is just a different interface for a normal automatic transmission. Shifting between N and D wouldn't cause any symptoms, it would just cause an abnormal amount of wear (same kind of wear as always, just more of it).

[FrugalFloyd]

Good sleuthing. I've managed >40 mpg on a nearly 1000 mile drive to Las Vegas & back in my wife's Hyundai Elantra w/AT and 2.0L engine. P&G between 50 and 65 mph on levels and downhills. Climb hills at 55 mph. That's how I did it.

[Larry1LT]

Just filled up at the only non-ethanol gas station in my county, which happened to actually be cheaper. Using my new found techniques of using N at stops and coasting while in N so far I'm averaging 45 MPG. That's what the ultragauge says, however, when I manually calculated my MPG on the last tank the ultragauge said 33 and my calculation was 33.35.

[FrugalFloyd]

Wow! 45 mpg is terrific. I averaged 43.7 mpg over 3600 miles in a rental Kia Rio this Spring, but it's got a much thriftier 1.6L engine. If I throw out the two tanks in SD where I was fighting 40+ mph crosswinds, my average rose to 45 mpg.rr

[pgfpro]

Originally Posted by ryude

Just filled up at the only non-ethanol gas station in my county, which happened to actually be cheaper. Using my new found techniques of using N at stops and coasting while in N so far I'm averaging 45 MPG. That's what the ultragauge says, however, when I manually calculated my MPG on the last tank the ultragauge said 33 and my calculation was 33.35.

Nice Work. Very impressive!!!

[Larry1LT]

Originally Posted by pgfpro

Nice Work. Very impressive!!!

Thanks, but now I'm scared to continue doing this. See, I don't think automatics like to be Pulse & Glided such as what I was doing today. I haven't noticed any noises or vibrations, but I read my owners manual and it states do not flat tow over 25MPH for more than 25 miles.

What do you guys think?

[FrugalFloyd]

That precaution is for towing/rolling with the engine off. As long as you're gliding with the engine on, your automatic transmission is being lubricated, and there's no risk of damaging it.

[Larry1LT]

Oh, thank goodness! I'm glad you guys are here to answer all my questions. Sorry to the OP for stealing his thread!

[theholycow]

Some vehicles don't cool the transmission as well at idle as they do when the engine is at speed. My wife's Isuzu is like that, and is a bad candidate for pulse & glide. The dash will likely light up a warning if the transmission is overheating.