I just picked up an 03' MCS and although I haven't done any actual calculations based off of the actual fuel I've used over given miles....when I'm cruising to work on the freeway at 70mph in 6th gear...and I reset the computer, it shows 36-37mpg along the entire 30 minute drive on the highway. From everything I've read, the MCS's get more like 30-32 on the highway. Are the MPG numbers that the car displays notoriously more than you you are actually getting?

Thanks!

Hey there,

I just bought a 2004 R50 MC base, and I have compared the computers MPG results to real calculations and typically for me, the computers results are about 2-3 MPG higher on average.

I always set my trip meter starting with a full tank, then fill the tank all the way back up at next fill (whether it's half, almost empty, whatever) and divide the miles I've driven by the gallons I put in. That is perfectly accurate. I think the numbers do not match because I have a feeling the cars computer cannot account for starting a cold engine, which is less fuel efficient. It starts reading right when the start the car like it's running at maximum efficiency. But try my method and see what kind of numbers you turn up, let me know too because I'm curious about a 03 MCS!

My 03 MCS reads 4mpg high consistently. The last 12 full tanks I have averaged 30.5 with 90% highway driving.

There you go!

My 2008 MCS indicates about 2mpg higher than actual over my last 3 tanks.

I get 23 mpg's combined City/Highway driving, consistently. I have a 2006 MCS. The new turbos get much better mileage than our supercharged.

I have a CAI and no other mods. If you research MPG's on this site. This is about average. On the highway, I can get 30-32, but any town driving will kill this number.

UfoMini

Thats the same mileage I get. We must both have lead feet.

From the data I had for my 2003 MCS, the MPG would read about 15% too high.

Yup, I've been getting just about the same #s...32MPG highway, display reading about 15% high. I'm putting a Detroit Tuned BPV on this Monday. Should be interesting to see what kind of numbers I'm getting then. I head around a 10% decrease.
Thank god the MCS is a pint sized sports car and not a mileage king.