I now have 20k on my 99 EV-GLS and have figured out 2 things that
influence gas mileage:
1.) If the dealer puts in too much oil when they change it ( 1/4" on
the dipstick)...mileage drops from 20-21 to 18-19. Always ask the
dealer to be sure use the right amount of oil and double check it
yourself (not easy to do) before driving away.
2.) Using high-test gas decreases mileage about 2 MPG
