There were two Jumpstarters added to the Autobot Transformers toy line in 1985: Topspin and Twin Twist. Their counterparts (sort of) were the Decepticon Battlechargers.
The Jumpstarters were the easiest toys of all to transform: they had a pull-back-and-go motor in their vehicle modes which, when used, raced the vehicle along the ground and then released a latch, allowing the robot legs to spring open and "jump" into a standing position. According to their tech specs, these two Autobots could change modes faster than any others.
The later Generation 2 Transformers included a handful of vehicles with spring-loaded transformations (which were later reincarnated as Tow-Line and Skid-Z in the Transformers: Robots in Disguise line), but they were much more complicated than these. However, the gimmick was that the Jumpstarters would jump from a racing vehicle to a standing robot on their own, while these later robots had to be picked up and have a button pressed. Coolness is pretty much relative.