those skylines are soo messed up. First off they recommend that you put straight nitrogen in the tires. If you run the stock tires in the winter you will void your warranty. You can't use the full power unless the gps within the car recognizes you are at a race track. I'm pretty sure there are some other things I'm forgetting but if someone gave me one I'd drive it.
Yeah, the electronic nannies in the R35 are ridiculous. Supposedly there are some aftermarket companies (Apex'i and Greddy/Trust) that are working on getting around that.