The Silvia LM is the only car you can win from the All-Night Enduro (forward SSR11), it's available in 2 colours however, red and green. I have the red one, but never seen/had the green one.
The other All-Night Enduro (reverse SSR11), has the Nismo GT-R LM Road Car as its only prize, it's only available in one colour: dark grey. But you can RM it so it's white with blue decals or dark grey with red decals. I have this car too.
The best way to describe the Silvia LM is: it's similar to the Xanavi/Daishin Silvia in GT2, with wide-body kits and sponsor decals and everything else you would likely see in a touring car, except it's an S14 Silvia, not an S15 like the Xanavi/Dasihin. It has a GTO LM style rear wing (connected to the trunk at the ends with no supporting beams in the middle). The red colour is a bit orange-ish, similar to the Dodge Copperhead Concept Car but with less "shine". As for the green one, I've never seen it, so I don't know, but I guess it's similar to the green FTO LM.
As to how it drives, it's a bit like the del Sol LM, nippy around corners and it grips really well although it will also drift when you force it to. Acceleration is great too, but the default gear settings' top speed is a bit low, you would want to increase it for tracks with long straights like SSR11/GVS. The only bad handling trait is sometimes it will understeer if you brake late, because it's still a bit heavy. Other than that, it's perfect, one of my favourites definitely.
I'll get you a pic if you want, but don't expect superb quality as I only have a crappy camera to take pics.