Sounds like the car is just downshifting probably from 3rd to 2nd gear to me.

Use the manual shift mode and start coasting at 35 MPH while in 3rd gear, then when you get close to 25 MPH downshift to 2nd gear and see if you get the same effect.

 

At that speed, it's actually the 4-3 downshift. When slowing to a stop, the car skips second gear and drops from 3 straight to 1.

Thank you all very much for the replies! So, guessing this is something I will just have to get use to? Hope my body can do it because it's weird and sort of gives me a sickly feeling (that lurching forward)

What you are feeling is fuel cut. The computer keeps the wheels locked to the engine and shuts off the fuel injectors, allowing the car's inertia to continue to spin the engine. It holds down to about 20mph and then the injectors switch back on and the car coasts farther without the drag feeling.

There isn't much that can be done to disable it, although you can blip the gas pedal when it's in fuel cut, or shift to neutral for a few seconds and then back to drive.

 

My GT is the opposite it will suddenly accelerate when down shifting from third to second.

 

That's what it's supposed to do when downshifting; keeping the engine RPM from falling too low and stalling out right? For example (random numbers here) when you downshift, let's say at 30MPH @ 1500RPM, your RPM will jump back up, to let's say 2000RPM, giving the feeling of accelerating. This same downshift will sometimes cause the vehicle to "lurch" forward depending on the RPM range the shift occurs at.

 

Normal downshifting.

It's also possible that you're noticing some added drag from the "smart" alternator charging the battery during deceleration.

 

Thank you all very much for the replies! So, guessing this is something I will just have to get use to? Hope my body can do it because it's weird and sort of gives me a sickly feeling (that lurching forward)

 

You just bought your Elantra right? I'd imagine/hope it smooths out as you break the engine in more.

 

There is no defeat for it, even in the aftermarket. All cars have it - even those with a manual transmission. The neat thing is how programmable cars are and how fuel cut is executed by different manufacturers. On my wife's Chevy, when it goes to fuel cut (gage shows open loop and 9999mpg), the computer opens the throttle a little so there is less resistance from the "dead" engine. Hyundai does the same thing but not nearly as much. On my Elantra, it goes to fuel cut on the highway and the throttle position reads just over 6% and as speed falls, it closes down to just over 4% - without any pressure on the pedal. As the throttle closes and there is additional resistance to spinning the engine, the car feels like it's losing more speed. When the tach gets to around 1200, it will downshift to keep the rpm high enough. With tightening CAFE standards, look for more aggressive fuel cut in future cars.

 

I really appreciate you helping me understand all this. I still have a mild case of buyers remorse but your explanations help. And what you said earlier about:

"......The computer keeps the wheels locked to the engine..... allowing the car's inertia to continue to spin the engine......."

That drag feeling is crap and will take some time to get use to for sure. Guess I'm going to get in the habit of throwing it in neutral when driving around city streets when I need to coast to a stop. Maybe my next car will be one from the early 2000's or late 90's?

I think Hyundai really should release an engine software update that does what your wife's Chevy does....... throw some fuel in the cylinders so your car doesn't feel like somebody suddenly hooked up a 20 ton trailer on the back when your speed drops to 20-25 MPH or so.

Hmmmm, maybe another way to cheat is just drive at the posted speed limit in the city and stop coasting and just get on the brakes when I need to stop.....no more coasting.

 

One more thing, think about the life of your brakes, being extended due to using them less, especially in stop and go traffic.:wink:

 

Good point. I just replied to dmlexpert and I'm slowly learning to adapt my driving habits to ease off the accelerator vs. just removing my foot.

 

My 2014 Sonata does the same thing, I'm used to driving an older car that just coasts so I'm not used to it. Does Your RPM go up as well when it downshifts? On my older car I wouldn't be able to notice it but I notice it on this car. Not sure if it's normal?

 

Forgot to close the loop on this. Like you, I grew accustomed to a car slowly rolling to a stop if I let my foot off the accelerator and was annoyed at this 'feature' of my new Elantra. BUT, I quickly got use to it and now use it to my advantage. It's just a new feel to get use to to. You'll adapt. As for my RPMs jumping..... I don't think so but honestly, I don't know. Never paid attention to the tachometer when this is happening.

 

The fuel isn't completely cut or the engine would die. On my two the commanded AFR in the fuel shut off is 15.15. Great way to increase you gas mileage if you use it. Generally at around 1200 rpm the fuel kicks back in. Taller tires will mitigate the feeling.

 

Hope this is the right forum.

I just bought a 2015 Hyundai Elantra Sport. Love the car except for one weird thing. If I'm traveling along at say 35 MPH and take my foot off the accelerator , the car starts to slow down (normal) to 34, 33, 32, 31, etc. until it gets to about 25 MPH then there is this bizarre (what feels like) the parking brake is engaging for few seconds as the speed QUICKLY drops from 25 MPH to 20 MPH then it just coasts and coasts like normal. If I stay around 20 MPH and apply just a SMALL amount of force on the pedal to maintain that speed and left my foot off the accelerator to let it coast, it doesn't do it. I'm going to test it again on the highway tomorrow at high speed but I don't think it happens if I'm going 65 MPH and let off. Only when it's dropped from 35 MPH or so and once it reaches 25 MPH..... BRAKE CHECK....just for a SPLIT second. It's very bizarre and almost feels like the rear disc brakes are engaging for that split second and the back end is dragging which causes me to lurch forward (well, causes my stomach to lurch forward which induces a sorta-sick feeling.)

God I hope there is a fix for this or some adjustment I can make somewhere to correct it.

Am I SOL on this?


In short, the answer seems to be, yes you are. I also have this problem, and I’ve had the car back to the dealership (for this and a few other issues). They have treated me like a senile old woman that likes wasting her time and money making the thirty minute drive for nothing. I took the car in a few weeks after I purchased it. They test drove it, said nothing was wrong with it, charged me for the labour to drive the car around the block, and sent me on my way. This is my fourth Elantra, and up 7ntil now I’ve never had an issue with the car or the service.