1.4 for 300???!!!!
I don't know which sites you're looking at (unless it's a used one) but from the reputable places I've only seen the 1.4 at pretty much a minimum of 400. Seeing you have a T2i, and that being a cropped body, I can speak from experience having learned the last several years on a 20D cropped body with a 12-24, 50, and 70-300, that for car shots... it depends on the environment you're around. If you want close-ups of parts, like the wheel or the grill or whatever, sure, the cheap 50 1.8 (or the 1.4 for that matter which I now own since my 1.8 took two drops before breaking..) will take razor sharp shots. On the other hand, if you want the full car?? Unless you're shooting mini coops, I would go for something tighter, as the others have said, either repair or replace the zoom- otherwise, you will be standing way far back with a cropped body to take shots and people may not even realize you're shooting the car (assuming you might be at an auto show or something). That was my biggest gripe about the 50 before I upgraded to my new 5D MIII

Now I love the 50.
Anyways, as the rest have said, for a 200 dollar range, fix the old zoom and get a 1.8 50 and lunch, or replace the zoom. The only other thing I would suggest is to look at some other off brand (tokina, tamron, sigma) zooms or primes and they may have something close to what could work. I don't know because with the exception of the 12-24 Tokina I had, everything of mine was Canon. Good luck
