Zwoobah

OEM O2 sensor is of unknown age. Only averaging 20.7mpg in 80-85mph highway driving - used to be closer to 24mpg (still running stock turbo and fueling).

Any other sensors to change? Coolant temp?

Fuel filter, fuel pump, plugs, air filter are all relatively new. Running M1 10w30.

UrS4boy

When in doubt, change the O2 sensor.<ul><li><a href="https://forums.audiworld.com/s4s6/msgs/150040.phtml">Link to G62 info in the FAQ</a></li></ul>

MiniMan

Hypermile that bish, Chris!

TabulaRasa

I normally get about 420/tank. That's 18-19 gallons or so per fillup.

Sloooo4esT

t-stat? I have the hacked Bosch o2 sensor working fine for 4 years

Zwoobah

besides, a 3800lb 290hp car running 20yr old EFI isn't exactly the hypermiler's weapon of choice

i have the miata if i really need to pinch fuel pennies. just want to make sure the S6 is running 100%, do not want to be turning wrenches after it gets cold outside!

Zwoobah

forgot that one, t-stat has been changed

MiniMan

Haha, touche sir, touche! Wrenching in the cold FTL.

kday

I picked up 2 MPG by tuning the LC-1 to switch at 15.5:1 AFR instead of 14.7. (This also got me through emissions.) I now get 19-20 vs 17-18 MPG for mixed driving.

I wouldn't do this on a stock car, but at least the setup I'm running (MTM 1+ w/ big fuel pump) runs too rich, and this solves it.

Note that this is a fix for a tuning problem on my car -- leaning out a factory-spec fuel mixture will at best trade off emissions (higher NOx in particular) for a slight increase in fuel economy.