We purchased a 2017 chevy spark with 40,000 miles on it and within the first two weeks the car will not accelerate for about 2 seconds and then will leap forward. when you come to a complete stop the engine will rev up and not go forward for about 2-3 seconds. this becomes very un safe since you can not depend on this vehicle to go forward when needed. i have taken it back to the dealer and they said there was an software upload to the transmission that should help. it did not help and i have researched that this is pretty common with these cvt transmissions. i will take it in again this week for them to possibly change out transmission. the complaints that are on this vehicle are the same having to do with acceleration problems. gm needs to look at this issue as a recall to help save lives.