But I think a car would be much simpler.
I've used LEDS on models before. LED bulbs are available in many sizes.
One of the easiest ways to carry current - especially in a confined space on a 1/25 car - would be copper tape.
https://rocketfin.com/2014/led-lights-models.jpg
Lighting a model depends if you want the battery to be in the model. ( a tight fite on a car model) . or externally.