Here are the skins that I was working on before I got convinced to switch to GTR Evolution. There are three versions of this car sporting various X-Sim logos and a carbon fiber / X-Sim green color scheme. The other logo areas were intentionally left blank so that you could easily customize thie skin, add your name etc.. PSD'd are available if you intend to customize the skin, just ask and I'll send them to you.
Before installing these skins, you need to install the WTCC BMW E90 Mod v1.0 and the v1.1 patch. You can download these files here-http://www.rfactorcentral.com/detail.cfm?ID=WTCC%20BMW%20E90. This is currently one of the hottst mods for rFactor (Top 5 ranked) I expect alot of leagues to popup using this mod.
After installing the E90 mod, download and install the Team X-Sim skins here -http://rapidshare.com/files/158554795/Team_X-Sim_BMW_E90_Skins_for_rFactor.msi
Now startup rFactor and click on the 'Player' button. Then select the BMW E90 series as shown below:
Next, choose Team X-Sim and one of the three X-Sim cars: