"maybe cause things werent > recalibrated after the PO put on 15 inchers..."

that's the key here. I have 28.4" diameter wheels (16" rims, with 225/70's).
That equates to 1.13% larger than stock so that's the number I times my
indicated trip meter mileage by to get an accurate read before factoring the
gallons added at fill up.

bob