easy
The Rally Car suffers from signifcantly less front-end damage because of the protection provided by the front bumper. The steel bumper fitted to the Race Runner is useless and unless you have a head-on impact, it provides no protection at all. It is also not legal for racing here in the UK and is usually replaced with the wider FG plastic one.
The other issue relates to the decision by MCD to use the Rally Car suspension on the original Race Runner. This was done (allegedly) to keep the importers/dealers happy - they could sell cars that used the standard off-road wheels made by HARM, FG, Lauterbacher etc. Clearly they made a mistake hence the re-designed suspension on the latest Evo 2 cars.
I have just (today) installed the Evo 2 suspension on my Race Runner and it would appear to be a step in the right direction, providing the new MCD off-road wheels are used.
The recent off-road racing would indicate that the Evo 2 cars are as strong as the high-end european alloy cars.
Clive