Had a 555 04, now have a 05 610 (buy back..... 70mph vibe). My 04's overhead was almost right on target in mpg, this one is always about 1. 5 mpg to high. Is there a quick fix for this? Anyone had this issue. Also I KNOW the mpg thing had been bear to death, but my 05 610 only seem to get less in the CITY, about 14. 5 vs 16 for the 555. On the hwy they both get around 21 empty on flat ground at 70mph, what gives?