This past week, my family drove from Colorado Springs to Iberia, MO (~2 hrs SE of KC).
2 adults, 3 teens and a cargo space full of stuff. In Colorado and the western half of Kansas, the Prius averaged 35-40 mpg. The rest of the way, I averaged 40 mpg.

Going home, we only had 2 adults and 2 kids, cargo space still full. I averaged 45 mpg. Dropped the girls off in Salina, KS to visit their father. Thereafter, I averaged 35 mpg.

It looks like altitude has a major effect on the Prius's mpg. Anyone seen this?

Infael

2004 Gray Prius with smart start/entry and VSC