Hello,
I've experienced the same issue, 4 times now. Always in Sport Mode, except I did have a couple of "soft jolts" in Comfort mode too.
I've had the car for almost 3 months now. First 5-6 weeks, I only drove in Comfort mode, not exceeding 3K RPM, during the break-in period. So I've only been experiencing the "problems" in the last 6 weeks or so.
The last bad jolting/jerking experience was this weekend, at a 4-way stop. In Sports mode, it's my turn to go, started off with good acceleration (but not aggressively at all, perhaps a third to half of the way on the gas pedal), and the car just started jerking/jolting like crazy, I thought I might break my front teeth on the steering wheel! I had so let go of the gas completely and let the car slow down... so there I am slowing to a halt, in the middle of the intersection, in my Benz GLC43, everyone staring at me of course probably asking what kind of idiot was trying to clutch a clutch-less car! VERY humiliating, certainly not the attention I was hoping to get driving around in this car.
I am very concerned about this, I am having the car checked out at the dealer of course. It's insulting actually that MB would let a car out of its manufacturing plant with these problems. I'm sure they noticed it during the months of tests they must have done? Considering the sticker price of the car, and that it has the AMG badge, this is totally unexpected and frankly unacceptable. The honeymoon has to last longer, no?! I previously drove a SLK55 AMG for 4 years, and that car was awesome, it got me excited and happy every minute I spent behind the wheel. Of course, I expected a difference in the driving experience between the SLK and the GLC, but I was not expecting the constant frustrations I have of not knowing how the car will respond to my request for it to accelerate, it is so unpredictable, I never know what to expect when I press on the gas pedal. Sometimes so sluggish, other times not, and then there are these massive violent jerks... Not normal to feel so frustrated when spending upwards of CAN $90K on a car... are the new GLC43 owners all feeling the same way?
I have other problems that I will be posting in different thread. Because this one is about the jolting/jerking problem, I didn't cover the other issues I've encountered.