I think we can all agree that Lego's own 42109 Top Gear Rally thing wasn't really all that. In order to improve it a bit I set out to build a rather popular car with it. Turns out someone beat me to the punch
Some trickery was used to create the GIF- the Porsche itself is stationary, while the light moves.
Functionally, the model is identical to the 42109, with some added lights. Luckily, performance has been improved by using Imurvai's Brickcontroller app. In a pinch, Lego's own app will work as well if you don't mind about the lights staying off. The dimensions are the based on the 42093 Corvette, so it should work with the 42098 car transporter. Underside with differential. (What, like it's hard?) Also note the extremely tidy cable management Given my typical production speed I should have a video out somewhere around christmas.