Hyundai Reviews

There’s every chance this is caused by a small amount of wear and slack in one of the joints in the driveline. If that’s the case, those joints and couplings need to be checked and the worn one(s) replaced, as continuing to drive as it is could see the driveline fail spectacularly at speed.

The reason you feel the jolt on the flat and not when you’re parked on a hill is that the driveline is relaxed on the flat, leaving a little slack for the thump to occur. When parked downhill, gravity has caused the driveline to take up that slack (plus your foot is probably on the brake, preventing the car rocking or moving at all) so the thump can’t occur and, therefore, isn’t felt.

I’m not sure that this is a common fault, but it’s certainly not unheard of. The stereo in a modern car is like any other electrical appliance; it has the potential to just up and die for no good reason.

But rather than simply replace the unit you have, why not shop around for an improvement. There are many, many, aftermarket stereo systems that will fit your car and will have superior Bluetooth functionality and more features than the stock head unit from 2015. You might find they’re cheaper, too.

A modern automatic transmission is a very complex piece of equipment with a whole bunch of parts that have to be talking to each other for it to work properly. Your best plan of attack is to have the vehicle inspected by a transmission specialist who is familiar with this transmission and should be able to diagnose the fault.

But it sounds like there’s something broken or loose inside that is not allowing the engine’s power to be transferred to the car’s wheels. This could be anything form an input or output shaft, a clutch assembly, torque converter or even the gearsets themselves. Perhaps the fault is in the valve body (the part that actually selects each gear) but until it’s torn down and inspected, you won’t know what’s going on.

The other major cause of a car not moving when it’s in gear is that there’s a broken driveshaft or CV joint. The symptoms can be very similar, so check the whole driveline before committing to repairs.