NFSUnlimited.net

When you unlock something with outruns in NFSU2, can you leave the event up and wait to get the reward until you get a car later in the game?

Nope not possible.

you get an opertunity for unique parts to apply to your car

Actually it is possible, but you must get that car before progressing to another level.

Jamaleni wrote:Actually it is possible, but you must get that car before progressing to another level.

Correct, unique upgrades are bound to game levels. So for example, you can install uniques from level three to any car that is available on level three. But once you move on to level four, you cannot install level three uniques anymore (even if you haven't used them).