So with no IMA battery with the check engine light and IMA light on you don't get lean burn? Huh, learning something every day.
Is your tire diameter same as original oem tires? If you have taller tires, the mpg would be better than gauge shows. Can you check your speedo to gps or road mileage signs?I'm getting about 5 litres / 100 km which works out to about 47mpg. IMA is still in, but no-assisting almost the whole time while driving. It's winter, I'm using Civic VX rims and winter tires. I have an upper-cat heat shield, I cleaned out the EGR, did a transmission fluid flush, and I have a KLR3CYL underbelly panel. I still need indexed spark plugs. My driving is mostly city driving, weather is averaging just below freezing. I do get lean burn, but sometimes it's difficult to keep speed up. The aluminum panel has helped considerably, so does making sure the tires are pressurized properly.