Yeah i looked at the booklet and saw 20 gal tank. Man i wish i could see 490 to a tank but that's not gonna happen to me lol on the freeway it puts an average 23.6 but in the city it's pretty bad at only 15-16 Could it be because of the Egr valve? it keeps throwing me the Check engine light and i checked the codes today and it spat out P0401 Oh yeah it's a 1995 executive series w/139K