ABS is a type of plastic used for making body parts. IF it's a cheap part it's gonna break easy, I know, I've done it.
ABS also stands for Anti-Lock Braking System.

I personally would not use fiberglass on a street car because it can get cracked easily and once it cracks it looks like ass. A lot of fiberglass kits sold don't have many layers. The more layers in the fiberglass the strong it is.
On a street car, I'd get a Urathne kit, more pricey then fiberglass but stronger. All of Wings West's kit are now made of Urathne I believe.