Yeah I know he’s supposed to be a generic tow truck, but even “generic” has to be based off of something right? I mean all of the other Cars in the films seem to be based off of some real life existing automobile but what is Mater based off of/ most closely resembles?
I believe he’s a 1951 Chevy. Also based on a 1951 International Harvester towtruck. One of those two. I think it says in Art of Cars.
He’s a Tuh-Mater, but without the TUH!
There’s a pic of the tow-truck that inspired him on the inside page of The Art of Cars. You can try post it on a car forum and see if anyone has the answer.
Wikipedia says:
Here’s an International Harvester according to Google Images.
The consensus on IMCDB is that he is a Chevrolet 3800. IMCDB is a movie car-identification database, and I have used it frequently because I’m a car-chase aficiniado. 
Debates on IMCDB have speculated him from a 56’ Dodge to a '55 Ford.
I think the truth lies somewhere in between. Mater is not so much an actual model as more of an amalgation of several, just like Lightning.
Oh yeah, I can sort of see the resemblance of Mater within those trucks.
Although you do raise a very good question thedriveintheater- what sort of car was Lightning based off of or most closely resembles?
Lightning is just a generic stockcar.
if it’s 2004, then he most closely resembles the latest Chevrolet Monte Carlo Stock Car, which has been the most commonly used stock car for such Nascar Races, or the Piston Cup in this case. The King is also another brief stock car, the 1974 Dodge Daytona and Chick Hicks an older version of the Monte Carlo, about the 1980’s version of Monte Carlo.
A rusty one. 
Mater is a Chevrolet 3800. You can look at it on google.
Mater is loosely based on a 1957 or 58 Chevy 3500. Body lines on front fenders and doors are from that model. Headline more closely resemble a 1957 Ford (Less eyebrow than the Chevy).
According to the Meet The Cars book, he’s a Haulital brand Hook 'em truck. I don’t think that’s a real brand or model of vehicle, but then again, I’m not as car-savvy as I wish I was…