Why is my new 09 Yaris MPG is so low

[yaris-me]

The main reason for low mileage is short trips. If the engine doesn't fully warm up the ECU runs the engine rich. It takes three to five miles for the engine to warm up. You need to drive seven miles or more to see 30+ MPG. If you do long freeway runs, you'll get 40 MPG.

[MadMax]

Originally Posted by yaris-me

The main reason for low mileage is short trips. If the engine doesn't fully warm up the ECU runs the engine rich. It takes three to five miles for the engine to warm up. You need to drive seven miles or more to see 30+ MPG. If you do long freeway runs, you'll get 40 MPG.

My Yaris warms up in under a mile (sometimes within a half mile), and we live in very similar climates.

I noticed as slight improvement in MPG after surpassing 5000 miles in my Yaris. I went from ~34-35 MPG to 36-37 MPG. Your car has yet to break in, so give it a little time and don't worry about it until you've at least done your first oil change.

Plus, driving 80 MPH will lower your fuel efficiency. For best results, keep it around 60 MPH. And during the break in period, do not drive at the same speed for extended periods of time, speed up and slow down on occasion as it helps with the break in. By the way, didn't you read your owner's manual? If not, you really should do so before anything else?

Also, is yours a stick or an auto? The auto will likely get a mile or two less per gallon. Plus, how you drive is a big factor. You can't drive it like a track car and expect it to give you great MPG in return.

[supmet]

Originally Posted by MadMax

My Yaris warms up in under a mile (sometimes within a half mile),

warming up and fully warming up are two completely different things. When the "cold" light goes off, it just means its warm enough to use normal shifting. Your engine reaches peak efficiency quite a while after the light goes off.