I have a 2011 Elantra with 7,000 miles. Since the very first day that I purchase the vehicle I had poor gas mileage. I started with 14 MPG in city and 25 on Highway. After a month I took it to the dealer and they told me that the vehicle is new and needed to be broken in. Now I am up to 17 MPG city and 26 Highway. At the same time, every time I made a slow stop the car will accelerate by it self. Today (9/15/11) the check engine light came on and I am taking the vehicle to the service department to find out what's the problem. I will post the problem as soon as possible. If somebody have the same problems please let me know. Thanks.

 

How do you drive? Heavy foot or grandma? Use the A/C alot? Stop and go traffic? Short trips? Are the tires inflated to the correct temps? Do you ride the brake or forget the release the parking brake?

As for the car acceleration by itself, that's usually a driver error. That's what Toyota found. People were pressing the gas instead of or at the same time as the brake.

Have the computer read to find the code causing the CEL. That may be the reason for the lower fuel mileage.

 

I live in NYC so you guys can imagine the traffic I am not expecting to get 29 MPG but at least 23 MGP. I do not ride the brakes. I never use the parking brakes either. I do on the other hand use the AC a lot. I am well aware of the Toyota acceleration problems but this is not the case. On my first post I mentioned about my engine light that came on but the same night around 7 pm the engine check light went off. I am really confuse, last time I took my vehicle to the dealer and told me that if no light is on then they cannot get a reading... I was going to take the vehicle to the dealer but I couldn't i made an appointment for next week. I hope the find the problems and fix it.

 

IMO the acceleration has to do with the combination of two factors:

1) brand new transmission exerting much more force than a worn-in transmission, even with no pedal use

2) A/C on means compressor running, putting more stress on system and causing more force to be exerted via transmission (from full stop). The car accelerates less in general when compressor is running, though.