1) Police spawns You go over a button that triggers a lua code which spawns a police car either trying to chase you or to go in a straight line to ram you. 2) Upside down gravity Like that video @tdev made showcasing the cars driving on the planet, I feel like this would be a cool idea if you could drive upside down on the tracks. IDK why, just some fun ideas I had.
A 100 mile tall ramp coming all the down to ground. A loop so big you need to go 500 MPH in a dump truck to make it.
Custom mesh pieces. Road and grass at side, bit of railings etc: Possibility to add trees on said grass. Custom level backgrounds like in light runner city. That could allow building longer roads for truck driving purposes for example.
How about mesh tubes with curves and bobsled style pieces. How about roller coaster track pieces. Like tube like this?