As I posted in a similar thread:
I would redo the LX series and not base it on number of cylinders, but instead on power. Caterhams are available with horsepower from 120hp (only classic has 105hp) to the 260hp CSR 260, all with very light 4 cylinder engines:
http://www.caterham.co.uk/showroom/index.htm.
Since these are the current cars, LFS should model these, not the cars of the past. If there are to be 3 different LX's, then I'd recommend 140hp, 200hp, and 260hp. The 260hp version should have bias ply slicks, as these are often used for wheel to wheel racing. The CSR 260 includes a dry sump oil system so it can deal with the conering forces from slicks.
Now they won't admit it, but Eric, Scawen, and Victor have made their own special developers version of LFS that only they can play. It has the LX8, nitrous oxide boost, motion blur, and slicks for all cars.