Flexible rack and pinion, rubber tread track or chain drive?

I’m creating a diy miniature roller coaster. One coaster car. I want it to travel at constant speed with a spring powered motor (Or other non battery or electric solutions). It will have hills and valleys and twists.

how would YOU acComplied this? I’m a beginner.
my brain says motor attached to the car on a fixed track like rack and pinion, but I need something flexible for the curves and twists

submitted by /u/Legitimate-Emu-615
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