I would say sometnig needs to be fixed. on my original 3.5 6VE1 I was making almost 20mpg. I put 3.2 6VD1 and was expecting a bit better gas mileage, but it's not happening. I'm getting about 17-18mpg. the measurements are taken on flat phoenix's roads in winter (phx winter ), and I'm cruising - rarely push it above 3.5K rpm