17. 5+ some hwy, idling,wot conditioins. a perfect world 65mph all hwy 19+mpg. i fill up when my light comes on it usually takes 28 gallons give or take 510 miles right around 18mpg. 17 w/ 3. 73 should be normal. remember i live in the flatlands right at sealevel. my mpg was 12mpg first tank 14 second and has increased ever since 8100 miles now. i have noticed a d/f with fuel additive around . 5 to 1 depends. i use redline and lucas.