The Car's computer control does not really listen to the input of the driver. Delay between the throttle and the car reacting is FAR TO LONG in Eco mode the car is a joke. Particularly when trying start up hill.

Eco mode does nothing other then relax the throttle response 'this is NOT A ANSWER FOR BETTER FUEL ECON" in fact because I take longer to get up to speed the car is in a less Optimal Gear Ratio and RPM rating. This COSTS ME MORE FUEL over all and my mileage charts proved it. Look it up, the ECO mode on this car only slows down throttle response. That's it. There is nothing more too it

its a light on the dash and a button to press... Nothing. Don't use it, it's a lie.

Next for 135 HP. (yep I've been robbed of 10 HP because my car has the PZEV Regulation on it YAY!!!) The car is gutless its an effort to drive highway at 60-70 because the optimal MPG range on 6th gear is much lower then that at around 53-55 so driving at 70 highway speed the car can't maintain speed and has to downshift constantly even on a 2% grade. My Honda? 2300RPM doing 75mph =36 to 38 MPG/ and its the B series 1.8 Liter motor not the 1.4 or 1.6 L motor. HOW?

It seems that if the AC and Defrost are both on and there is a sudden need to accelerate the car completely stalls. For about a second or two there is a sudden (immediate) loss of power but the car will just as suddenly reset and drive normally. There is no surging before the problem or after. It is as if someone activated a switch to cut the car off for about 1-3 terrifying seconds (especially if this ever happens in a busy intersection).

NOTE: This has happened about 5-6 times in the past week. We have had it to two (2) mechanics who cannot duplicate the problem so we cannot fix it. PLEASE ADVISE.

This issue has actually happened multiple times: my car looses acceleration when I'm driving on the freeway and the RPM's rev up but the speed decreases. It is horrifying and I'm at a point now where I can't really drive it on the freeway anymore, I don't know what to do. It is still under warranty but the service department (so far) is unable to resolve the issue. They currently have it and I am praying for a resolution.

Most recently my brakes also locked up/made a grinding noise in addition to the loss of acceleration which I'm sure is in relation to this problem but it may be another issue altogether. It pains me to continue to make payments on my car while it is having such major issues. I am so disappointed in this car. I had a Honda for 15 years without a single issue. I wish I kept it longer or bought another Honda.

I really urge anyone who may be reading this who is having similar issues or know someone who is to take the time and right a quick review as this is the best way to alert dealers of this issue (besides talking directly) and just getting the word out that this IS an issue and it isn't isolated to just you.

Went to start the car and it sputtered and hesitated when in drive. Car did this for a few minutes, then the engine light came on. Gas level was above a quarter and I was on my way to get gas. Filled the tank up and the vehicle still sputtered and hesitated check engine light stayed on for a few hours. The car drove well for a day, and this morning 6/1/15 it sputtered and hesitated some more. Taking in to the dealer.

Online research showed several Hyundais with the same issue. One person had a cracked fuel pump and the crack was below a certain level so it only happened when her fuel got to that level. This caused a bad sensor. Hope the solution is as simple. Been having trouble since I bought the vehicle new in 2013. Dealer has yet to find a problem. This is very dangerous because it could shut off during highway travel and cause a death. Filed a complaint with Hyundai but I haven't heard anything back yet.

After 7 months and @7200 miles the love affair ended. All of a sudden getting on the freeway, or attempting to pass someone became a crap shoot. At @ 40MPH the car will simply refuse to accelerate. I'm on the gas pedal but the engine is not getting the message. If I'm already doing 65 or 70+MPH and have to slow down, the car will do the same thing at @60MPH when I try to get my speed back up. I've had to jump back behind the very car I was trying to pass on a few occasions.

Of course! This is an intermittent problem that the dealer can not isolate or explain. The car has been scoped and everything is within manufacturers parameters. So for the past year and 9 months, every time I get into my Elantra........it's like driving a box of chocolates.

The acceleration issue coincided with a huge drop in gas mileage, but that's another unresolvable complaint.

took car to dealership said everything checks out, they want to take my car for a technician to drive around until the problem happens, told them this is an intermitted problem could happen 1 day or week never know when this is going to happen. When it occurs the engine lights do not go on, when you are pushing on the gas pedal, it likes it isnt getting any gas, no acceleration at all, car loses momentum. Told dealer feel this is a dangerous situation. I asked dealer if they had a meter they could hook on my car while I drive it, Sam from california said it would cost hyundai too much money to have meters to do that. I explained I dont really feel comfortable giving my car to a complete stranger, this is a large investment for me, told Sam that I dont even let my childred drive my car. They insist this is the only way to do it. I asked them well ok if your mechanic drives the car and it does it, how is he going to detect the problem, because he will be on the road and wont be able to have the computer on the car while it is doing it.

Is there anyone else out there that has this problem and how do you feel about giving your car to a dealership to give some stranger your investment and no information on him as a driver. I NEED HELP IF ANYONE HAS ANY SUGGESTIONS THANK YOU