Dani Amengual, a Kickstarter creator from Spain, has solved this problem. They have a Kickstarter called
On the Road . . .
58 assorted road sections, along with a sectional bridge that will be awesome in an arena. (My car can be shot into flaming wreckage from a whole new angle!) Scale might be an issue – the pieces are in 1/48 scale.
Car Wars is 1/72, so the railings on the bridge, the clips that hold the roads together, etc., might come out weak or non-existent, so I recommend printing the downscaled clips in resin. I've backed this project myself, so as soon as I get the files, I'll be able to make suggestions on how to address the scale problems. And the Kickstarter is only $7!