TwoTonic

Even with fuel prices moderating a little, I've been tracking the A8 mileage more closely recently.

I've got a 300 mile round-trip that I drive weekly now for a consulting gig. Of the 300 miles, about 100 of it is 75MPH freeway, 150 of it is 65MPH two-lane highway with little traffic and 50 of it is stop-and-go suburban driving at 25-55MPH with a few lights.

The '97 A8Q 4.2L is consistently getting 29.1 MPG, just driving the speed limit, and the 2001 A8L gets about 25.0. Driving styles, speed, weather, wind are usually pretty comparable.

So, I'm wondering whether the difference is entirely due to the A8L weighing a bit more? Seems inconsequential, given it's only a couple hundred pounds. The other factor is that the '97 runs a 2.73 Final Drive Ratio and the '01 runs a 2.91.

Anyone want to venture some thoughts as to whether the ratios or the weight are a bigger factor?

My love for the '97 has taken a big jump since the fuel price run-up... Heck, 29MPG is better than the wife's TT gets on the same route. Anybody else seeing better mileage on the early D2s?

Happy Halloween!
TT

PaulW

That's if I feather the throttle constantly, and keep the speed to 65 MPH. It's the ratio that kills you.

TonyA8

But the moment I hit the mountains in Kentucky, it starts to drop. Alot depends on the terrain. The flatter it is, the better your mileage.

There is only a 100 lb difference between the A8 and A8L. At 70mpg, I do about 2000 rpm.

TwoTonic

Those shorter gears in the S8 also really help your performance.

I've been lusting for an S8 for awhile to add to the fleet-- and have been curious how much of a hit the mileage takes for getting the 3.73s and sweeter motor in your S8.

Mex77

Mine is around 26, and it´s a S8 -01 tiptronic.

PaulW

You can't get 26 on a S8.....what speed? 51 MPH?

Unpossible.

OOOOya

My S6, geared the same as an S8, get's the same 22.5 on the best day it's ever had - across western Kansas with a tailwind driving the KS 70 MPH speed limit.

TwoTonic

Velocity is certainly A factor, but I actually don't see much mileage difference between 65 and 75. Cd is relatively low and a smallish cross-section relative to other 'full size' cars.

The ratios would seem to be the big factor on the S8. The '97 really surprised me that it could consistently deliver close to 30 MPG, but the tall gearing makes if noticeably slower off the line than the (heavier) '01 A8L.

Mex77

Hehe, well as I live in Norway, the speedlimit is 50mph (80km/h), even if i drive 56mph (90km/h) the consumption is the same.
But when i pass 65mph the consumption rises.

PaulW

Amen