Not only do I work on diecast car model collectibles for a living I also collect. I mostly collect modern street machines, and Pro-Touring styled diecast and of course Mustangs. Although the 1968 and soon to be released 1969 Pro-Touring Camaros will be the favorites of my collection (I'm biased of course) but I do collect some Hot Wheels too if it's the right subject matter - Hot Rods and Muscle Cars. I like the new G-Machine stuff, it's a little more straight forward and realistic in the pro-touring sense than most of the stuff on the retail shelves. The Pro-Rods are cool but most of the body mods on their stuff seems a little overdone for me. The G-Machines seem to hold more of the Muscle Car flavor than street Machine as far as the body mods are concerned. Depending on your own personal tastes the wheel and tire combo might be too outta proportion. Being a Hot Wheels TOY and at the scale it is I think it looks cool! I have about 6 of them and they look great sitting together. Some of the wheel and and paint schemes are a little off looking but overall again they're cool. Here's some pics.
They look pretty good, but I stick with 1:24 or 1:18 scale. I occasionally go larger like my 1:8th scale Muscle Machines '57 Chevy and '69 BOSS 302 Mustang R/C cars , which is about as many 1:64 cars that I have.
Disclaimer: There's a whole other group of designers that do our paint and graphics, but I have put the word out about certain "rules" so I trust you'll see a change. A lot of what I have worked on still hasn't hit the shelves just yet (except the D-Rods, which I did have a hand in.)