Dude in a car threw an apple at me

So yesterday I'm descending a hill in the countryside, I'm in primary position but going fast - just over 50mph.

I can hear this souped up car behind and when I need to slow down for some turns I move to the side to let him pass. As he passes me the passenger leans out the window and chucks an apple at me pretty hard. It hit me in the bicep and it actually really stung - the speed I was travelling and the force of the throw made it feel more like a brick (I've got a massive black and purple bruise on my arm to show for it). I wobbled a bit and very nearly went into the bank but thankfully stayed upright.

I was so angry at the time that I tried to chase them down, I swear I would have put my fist through the car window if I'd caught them up so its probably a good job I didn't.

The guys in the car were young, probably about 17. I memorised the number plate and the car is very distinctive, I'm pretty sure I've come across the car before - it makes a very loud and unusual engine noise. I didn't have a video camera.

Any advice on what I can do? Ideally I would really like to find out an address based on the number plate and go there to give them the apple back, show them the black and purple arm they created, and talk to the driver's parents. Failing that I guess I could report it to the police but to be honest I have no faith in them doing anything about it.