Any name that seems to fit the character of the car. In hindsight, based on personifying the car's flaws.

One was a Saturn SL2 that had a leaky exhaust, sometimes hesitated to start, and the automatic transmission shifted aggressively. Oscar, because it seemed grouchy all the time.

Another was a manual transmission Volkswagen Passat 2.0 with a tiny turbo and some neat safety features that still worked, including automatically holding the brakes for a hill start to prevent rolling backward. Not particularly fast, but once it got going it just kept accelerating up through the gears, as if rising to a challenge. I named it Walter, it just seemed to fit.

My current car is a 2014 Ford Focus with the "bad" transmission. It needs to either go or stop, asking it to accelerate too slowly burns up the clutches in a hurry, thus the terrible reputation for the dual clutch automatic. The harder I accelerate, the better the gas milage, up until it starts spinning the tires.

Idk what to call this one.