Your Toyota numbers are definitely skewed. I have a 2005 Tacoma and a 2006 4runner with the same six cylinder that get 19-22 mpg. The 4runner has a computer display mode that shows mpg at all times and there is a huge drop even on the highway if you use cruise control over 80 mph. My best was 22.9 at about 63 mph on a flat 100 mile trip.