Did you pick up a new hybrid? I believe the break in period of my HCH II was around 500 but I noticed an improvement in mileage around the 2-3000 mile mark. I've driven the car non-stop from LA to SF a couple times and been able to secure upper 40s and a 50 miles per gallon driving around 68 miles per hour. When I know the ride is flat I put on the cruise control to save my legs/foot. Some folks find the car uncomfortable but I don't, even with 40 psi in the tires. 32 is standard from the dealer. My first oil change was at around 8000 miles. It's a great car and with each month that passes and the gas prices rising, I'm really glad I bought one.