There is software you can download that unlocks it using the USB cable, although i don't know exactly where to get it (Google will be your best friend here).
Also why not have some set components in all the engines? That way it evens it up to a certain degree but also allows the manufacturers to fine tune their engines for every little bhp they can squeeze out.
The Hillclimb addon will be released after the 1.0.3 patch, I believe half the reason is simply that Kunos wishes to release it to the public using the much improved 1.0.3 version
Firstly, the netcode is much improved over V1.0.2 - there is hardly any join lag and the FPS is alot more stable (Some peoples machines have seen a good increase in FPS as well as it being stable). So now your online races won't get ruined when either someone joins or because your FPS is jumping from 60 to 5! (Im sure Moose will back me up here )
Secondly, the System Requirements are exactly the same as v1.0.2 - the only thing is V1.0.3 should allow systems nearer the specs (e.g. slower computers) to run smoother.