Generally gm is garbage but get proof of highway mileage, can't tell you how many times I've heard that. Have it gone through by a mechanic & ask if their scan tool can has the ability to check average speeds. If it has more stop & go on it that thing isn't going to last long before that tranny departs for the scrap heap.

There was a dealer level one where my buddy worked & on certain models it could tell you that along with give throttle percentage graphs. When one of the lot guys did some damage he pulled it up & it showed 90% throttle along with how long he was driving like that. Needless to say lot guy got fired as the entirety of the two miles it was floored.

"I only drive it on the highway" comes with just about every car I've checked out, either that or "what do you want, for this year it's amazing" meanwhile the frame is cracked & it has 400k miles on it🤣