The Rocket Cars were in available in RCT1 for the Steel Mini Roller Coaster.
Interestingly, in RCT3, the length of cars can cause itself stuck to the start position of ride, the operation is quite different by launching with only little speed, even U-shaped small curve proves the ride vehicle pass or failure (Rocket and Toboggan can go through while Mini Cars cannot). This can solve for universal vehicles by adding a gentle drop to make the car speed enough to reach chain lift.
Trivia
The Russian Cars vehicle from Wacky Worlds is actually based on the East German car Trabant 601.
In Real Life
The Mini Roller Coaster is similar to a Pinfari Zyklon Z40. Both of these coasters have single-car trains and compact track, however the track style itself looks more like a Mack Rides Family/Junior coaster.
