Every time I release the brake pedal after sitting at a long red light the car shakes and shudders, sometimes really hard, and sounds like it’s choking for a few moments before I am able to accelerate. It sounds and feels and acts as though it is going to stall but it has not yet. The effect does not happen when the air conditioner or the vent are being used; only when those are off. It varies from mild to really strong.

It took multiple trips to the dealer for them to determine that it is normal not just for my car but for all 2016 Sonatas. It is a feature where the transmission shifts into neutral at long stops then re-engages in drive when the foot is lifted from the brake pedal. The purpose is said to reduce engine load.

I think this is a safety concern is because when a driver removes their foot from the brake and the car’s brake lights go off, it is a signal to the car behind them that they are about to go. But the wait time required for the shaking and sputtering to stop before the gas pedal will work results in “mixed messages” to the driver behind, thinking that you are ready to move forward but you’re not really ready yet, and may result in a rear-end collision.

Car shudders when accelerating at low RPM (<1500). Sounds like the engine is lugging due to insufficient power. It hesitates to downshift even when I increase the throttle. When it finally does downshift, the shuddering goes away but if the RPMs drop below 1500, it starts to shudder again. The shuddering is very noticeable (I can both feel it and hear it). It's downright embarrassing to drive with passengers in the car. My car now has 4700 miles on it and the problem persists. I honestly wish the check engine light would come on as this is NOT normal. There are least two other people who have reported this problem over at www.hyundai-forums.com.