Thanks for the comments.
WallyTWest, the vehicles are Matchbox Models of Yesteryear. You can pick them up pretty cheap from EBay. I got about 20 of them for £20 but to be honest, that's way more than you'll need. They're a bit on the big side too but look ok on the board. I'll take a couple of picks later with some minis for size comparison.
Some people use Solidio.
There's also the some coming out for the Chicago way, they're resin I think and around £20 each but look really nice.
Cheers BF.