ANSON made the 1/12 RT/10 models. I have those in Red and White/Blue and an Orange Concept Car in 1/18. ANSON also made a Blue/White in 1/12. I haven't seen any 1/12 or 1/10 models in Gen 3,4,5, except for the remote control car above.
My collection of 1:18 cars stands at 124, including all of the AutoArt GTS-Rs and a good number of air brushed Bburago's. I also have a number of 1:24 and smaller cars, but 1:18 was my primary focus. It got to be addictive so I had to stop buying them for a while.