On my 2003 S40, the owners manual states that the gas tank holds 16 gallons, but whenever the fuel gauge shows about 1/8 of a tank left and I go fill it up, it only takes 10 gallons, does anyone have an explanation? Also, everywhere I look, the '03 S40 is said to get 27 mpg, but the computer is telling me I'm getting 35 mpg. I'm currently testing it manually, but was wondering if it was normal for S40's to get much better mileage than claimed.

 

It sounds like your gauge is off. Do you ever wait till the low fuel light comes on?

If you have good driving habits, you can beat the rating by as much as 20%.

 

There is a thread on swedespeed where the owner pulled the sending unit and recalibrated the float to show the true fuel level.

My 2001 is the same way. With the gauge on empty there is allot more fuel left.