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2016 Scion TC low gas mileage


Topic starter

Hi Scotty & Everyone. I recently bought this car. It's fine except I only get 23 mpg's average. It should be 23/31, I do mostly highway driving, using "ECO" mode and cruise control. Automatic/ 38,000 miles.

Suggestions please.

Thank You 

4 Answers

The most useful and immediate information would come from a scan tool that has Live Data capabilities. More specifically, both Long Term and Short Term Fuel numbers would tell us if the vehicle is running excessively lean or rich. (Anything over 10 percent plus or minus, particularly with the Long Term Fuel Trim indicates trouble ahead. The Short Term number fluctuates constantly).

You might have a dirty Mass Air Flow sensor. You might have, as stated above, a dirty throttle body. It's easy and cheap to clean these.

If the vehicle is running "rich," because these two are dirty, then you'd want to attend to them promptly. A rich fuel mix will shorten the life of your catalytic converter and your engine.


1. Are your cold tyre pressures good?

2. Is your air filter clean/new?

3. When was the last time your throttle body was cleaned?

4. Do you change your oil regularly?

5. Do you have a sedate driving style?

6. Any codes?

7. Any aftermarket parts fitted?


1. yes
2. yes
3. no idea, just got the car.
4. it was just done before I bought the car a month ago.
5. yes
6. no
7. no

As @geriscan mentioned, clean your throttle body & MAF sensor using Scotty’s video as a guide. Also, try & look for the tC’s forum online & verify if the others on there are getting any better gas mileage than you are. Oh also, when you’re on a flat road (preferable empty), try & shift into neutral and watch the car’s behaviour. It should coast smoothly & gradually begin to lose speed. If it abruptly starts to slow down, it means your brakes are dragging and that could certainly affect fuel consumption. Keep us updated. Good luck.


What's in the car? meaning, is trunk and back seats empty or are you hauling around unnecessary added weight? 

Also, are you in a part of the country where it's still cold? If so winter blend gas gives lousy gas mileage. Once summer blend is available you should get better mpgs.

This post was modified 4 weeks ago by toyotagrl

Nothing/ no


During the months here when gas is winter-blend my mpg's go down a few to about 25, and during warm weather when gas at the pumps is summer-blend my mpg's goes up to about 28+ and this is driving a 2019 V8 Camaro SS. Here in NC the switch over is mid-May and mid-October.

So your tC is 5 yrs. old with 38k miles. Hasn't been driven much over the 5 yrs. that's 7600 miles per year or 633 miles per month. That's not much, so it's been used to being driven very little and short trips. Also, don't go by what the mpg's the car says, there's quite a bit of error margin. I calculate at each fill up and reset my trip A each time to figure real mpg's.

One thing the 23/31, is under ideal conditions and the best numbers that were returned during testing to report to the gov. However; you should be getting better than 23 mpg's. Avg. combined real world is probably more like 26. Heck, I'm getting better mpg's with my V8 muscle car, so something is holding it back or may just be the way your particular tC runs. But it is at a point to be changing the trans fluid, and consider cleaning the MAF, throttle body plates, change fuel filter, have injectors checked out. How much you want to do to get a few more mpg's. Shoot, you might also just need to take it on a longer trip and "air it out".