The thing is that quality cars take quite some time to make. Generally speaking, it involves making and texturing your own parts, levels of details (LODs), and fixing random bugs and mistakes. Unlike 99.5% of "vehicle modelers" out there who just slap crap on a car, call it a day, and release a pack of 10 cars every few months, while the few people who make decent cars take months or years on a single car to make it just right, an example being Desmond who has been working on his fpiu for over 2 years. On another note, the fact most people try to slam out as many vehicle releases as possible leads to people acting like motive because it gives people almost instant gratification for new things, and when they're told to wait a bit it makes them cynical.