m0rs

http://auto.howstuffworks.com/how-to...l-economy1.htm

"But if you're on the highway, driving 60 miles per hour instead of 70 mph will save you 2-4 miles per gallon over the duration of your trip."

Is that really true? Does that not depend a lot on the car? Is that true for the LS?

RA40

iTrader: (6)

Who can drive that fast in So. Cal?!!! Most mine is slugging at 15-25MPH.

I don't notice much difference from 65-70 in MPG. On my Oregon run, I didn't detect much between 65-75 for that matter. My best mileage run was done at 75 MPH and the car did 26.8. That was some 60K less miles on the OD so the engine was fresher if that had any factor. Forget weight, I had like 120#'s of luggage/camera gear in the trunk then. Didn't have the heavier wheels either.

Sanpete

The 2-4 mpg estimate from the link is probably true for most cars, but V-8 cruisers like the LS are designed to be efficient at higher speeds. My impression is that I get better mileage in my 98 at 75 than 65, but that's from looking at the computer readout of current gas mileage, which isn't all that reliable a method. I get pretty good highway mileage, about 30 mpg, trying to keep the speed at about 80, with a light foot for acceleration. (I think I'm more efficient without the cruise control, from what I can tell so far. It reacts more quickly to slight deviations from the target speed.) The 98+ models have a fifth gear, so that probably raises the optimum cruising speed. But I'd think the optimum for the earlier models is still closer to 70 than 60.

tbilisi79

I was always under asumption that the
Low RPM will yield best MPG.
So in 5th going about 1500 at 50 mph will get me 29, 30 mpg.
But I have also done 75 mph and gotten 28mpg as well.
I may be wrong, but the torque curve comes into play as well.
You would have to calculate wind resistance, torque curve(amount needed to go through wind at a particular speed).

But are we really counting dollars here?? I hope this is purely for arrguments sake.

Sanpete

Dollars, pollution, global warming--take your pick.

turbosix

the 1g ls have a .29cd which is very ****ing low....

i notice no real difference. dallas to houston trip and dallas to san antonio trips ending up 25mpg while going 85-100 the whole way. the car isnt even supposed to get 25mpg going by EPA ratings.

lexusnutt

Glad to hear I'm not imagining things! Like you, I've recently gotten close to 30 MPG cruising 75-80, but tend to use cruise control. I used to have a '95 and the 5th gear makes a BIG difference!

ttyR2

I'm averaging about 23mpg with highway and limited city driving in my '90 LS400 @ 313k miles on the odo.

Broker404

I've noticed a big difference in my 99 LS400. when I take a trip and keep the cruise control between 65-70, I get about 31-32 mpg. but when I set it to 77-79 mph, I get 28-29. and at 50-55, it goes way up. but I'm not sure how much because I've never taken a long trip set that low before. as I have with the other two speeds.