It wasn't a world record for cars in general but for production cars. Performance Power Racing builds and sells that exact car to the public.
I was kinda surprised that there wasn't some kind of spoiler on it to create more down-force, but I guess that really isn't necessary for straight line speed. I think it might've helped around 90-140 when he was still getting wheel-spin. I'm sure he wouldn't have gotten much more speed though, if any, because he was right at red line at the end.