I'll have to do this soon.
BTW, US peeps, if you want instant access to the Challenger in Forza 4, order from Amazon or Best Buy as all the other retailers are waiting until Forza Horizon is released to give out the codes for it.
Speaking of pre-order bonuses, here's a list of what stores give you what car:
GameStop - Ferrari 458 Italia
Amazon.com - Aston Martin Vantage
That's all I've seen for now.
I pre-ordered mine through Gamestop but did not get a redeem code for the Challenger in Forza 4.
You'll get the code with Horizon. I think Best Buy gives you the code right now.
For the Challenger? I know I'll get the code for the Ferrari 458 with the game but I was under the assumption that I should have received a code for the Challenger after a submitted my pre-order. Either way it's no biggie now, if I do get a code for the Challenger later on, I'll just give it to someone who doesn't have a code.
No UK LCE preorders as yet. Really annoying because I want the Horizon Challenger.