I'm hoping someone can help me out on this issue, I have a 2007 RX400h and I'm getting 15 mpg. I live in Toronto, ON Canada. It was extremely cold here for 2 weeks where temperature was -20C (-4F). I kept inside cabin temperature around 25C (76F). In the summer time I'm able to get around 21 mpg but I think a 6 mpg drop in the winter is ridiculous and was wondering maybe theres something wrong. I drive close to 25 miles per day (to work and back combined) all city driving. If someone can tell me how to fix this issue that would be greatly appreciated.

 

Have you changed your oil and air filter recently? Getting rid of dirty clogged air filter helped improve the mpg by about 1-2 mpg.

Also, have you checked the tire pressure? If you increase the psi to above 30 in the tires, that can help get about 2 mpg