If you have a car that's older than this, then that's no problem, but it can't be sold once you're done with it. The benefits are two-fold:
Increase the safety of the average car on the road by bringing the minimum safety standard up slowly over many years, since newer cars are generally safer.
Decrease emissions of the average car over time, as newer cars are generally more fuel efficient.
Further, since this only applies to purchase, sale, and transfer of ownership, current owners of old cars are not effected.
Bang. Awesome policy.