[husker boxster]

I've gone to O'Reilly's to have the codes read on an Audi TT. Would think they could read the basic stuff on a Box.

Also, you could have a MAF or O2 sensor that's not quite bad enough to throw a CEL but is jacking up your air / fuel mixture. Does your engine idle smooth? Is there any black soot on your exhaust tips?

You might also try disconnecting the battery for a couple of days. When reconnected, your computer will start back at factory settings.

We do have similar Boxs so our mileage should be comparable. I will state that my city driving rarely consists of stop and go / bumper to bumper traffic. I go to work early and avoid the rush hr stuff (what little we have compared to other cities). And my readings always come from the computer. I know it might not be 100% accurate, but it's close enough for me.

I drove the Cayman to KC this weekend. The computer said 27.6mpg at 75mph.