At 6,900 miles/4 months old, I just got 29 mpg at 80 mph on a 370 mile trip, with four complete stops each way for toll booths in Illinois. Is this poor, average or good? No A/C use, hit 90 for about 15 minutes to make up some time. Thanks. 2003 CLS6.

 

That's pretty typical. I've gotten that with A/C at a steady 80. I think 31 or 32 is possible.

 

Yeah... slow down and you will hit 30-32MPG easily. I get 10-15% better mileage going 70 instead of 80.

 

I averaged 30mpg @ 80mph awhile back on a long trip, with a high of 33mpg on one tank. We're all right there.

 

I hit 31mpg the other day coming back on I-294, and I forgot my I-Pass, so I had to stop at every toll booth.

Contrast that to the 15-16mpg I get in the city...

 

Just did a 2000 mile trip to southern and northern Cali. My best was close to 29 mpg and the worst was about 22 mpg. Back in AZ, with all city driving, I get about 19-20 mpg. Driving speed varied...never got over 100 mph though (no balls, afraid of cops).

Wished I could have broken 30 mpg though.

 

are you guys dividing by 17.1 as the size of the tank? ... i never get close to 17 gallons... usually 13 or so..

Elliot

 

Elliot, this way is more exact. you don't need the tank capacity.
1- Fill car up full.
2-Set trip odometer to 0. Drive and use up most of the gas.
3- Refill up full again like before. Write down # of exact gallons you just refilled up with. say 15.3 gal.
4- Divide the miles you've driven since you set to 0 by the # of gallons you just put in, walaa!--- mpg.
so if you logged 320 miles/divide by 15.3 gal = 20.91 MPG!