That would only be temporarily helpful. The remaining Car Series that I've yet to unlock all feature either Super or Hyper series cars, and if the Sports series are any indication, you will only finish 1-2 chapters max before you hit a ridiculous PR wall again.
For Underground mode, nothing except the Koenigsegg is eligible for the last races of Chapter 14. That's how crazy the PR requirements are. I don't see them handing out the Koenigsegg as a prize anytime soon, so in the end I'll still be stuck.
Either the XP or PR requirements need a rebalancing, or the gold crates need to give out better parts. But it's probably not going to happen because of all the microtransactions.