I know this is a pretty terrible and possibly wide-ope topic, but I have been getting /awful/ mileage in my 1999 S70 since this summer. I am looking at 16-18mpg in town, and maybe 20mpg on highway. Prior to this summer, I was looking at 24/30mpg. I've had it to the mechanic for general fixing, and they didn't find anything obviously wrong. The spark plugs have been changed about 15k miles ago, no codes are showing up when scanned, tire presssure is good.

Are there any obvious problems that I am overlooking that could cause such a drop in mileage? Are there any simple fixes that I could try to improve my MPG?

I know that there are a million things that this could be, but if anyone has had similar problems and could share some information, I would really appreciate it. Thanks! Happy holidays!

 

Please read the 850 MPG sticky. It has a lot of good info. The most common problem is the use of after market spark plugs and not having them gapped properly. Use Volvo spark plugs.

Good air filter, 91+ octane, no brakes sticking, etc. Volvo says that these cars should get between 18 / 26 mpg.