Declining MPG in 2008 Toyota Yaris Hatchback



I have a standard 2008 Toyota Yaris Hatchback that I purchased in Dec 2007. Up until recently it has been averaging 37 mpg however in the last two months it has steadily been declining to 26mgg as of yesterday. The car only has 11,000 miles on it, any ideas on what could be causing this? Any ideas would be helpful?


Two obvious things to check are: 1) is the engine warming up completely? A thermostat that is stuck open will prevent the engine from warming up and the gasoline mileage will drop. 2) Check to see that the tires are inflated to the recommended pressure.

Check your mileage over a couple of tanks of gas. It is possible that the pump shut off too quickly one time and the next time you put in more gasoline for the miles traveled.


The Yaris has tire pressure sensors in the wheels and a low pressure light will come on if any tire is low.
Your tires would have to be really low to affect gas mileage that much.

Any check engine lights on? Perhaps have a shop check for stored computer codes.

It’s also possible that you are driving more aggressivly as the car stops being new or that traffic and weather conditions have changed. Rain kills gas mileage from tires having to plow through standing water. Ditto with snow. Traffic jams kill gas mileage because you sit there and idle.


3: your town has gotten it’s supply of winter blend fuel


I’m with the tire people. My 2007 yaris hatchback is very sensitive to tire pressure. Mileage can drop from 32 avg to 25 w/a drop in tire pressure from 32 to 25. I don’t ever get 37mpg, but they don’t call me Dr Demento for nothing.