What's your favorite casting from childhood?
AMC Gremlin. The 70's had some great castings, but this was my favorite.
My favorite casting from my childhood wasn't a Hot Wheel, or even a car for that matter. It was this guy, UFO Robot Grendizer.
My favorite casting from childhood was this guy. My cousin and I used to play with these cars all day every day in the summer and would argue over who got this one. His brother was in a wheelchair, so they had a wheelchair ramp coming up to their house. Of course we raced the cars down the ramp.
I am showing my age as Hot Wheels weren't around until I was ten years old, on the plus side it meant my first Hot Wheels was one of the sweet 16. A maroon Custom T Bird with matt black roof, for a kid from the UK to have such a cool American muscle car was brilliant. Sadly I don't have the car now, I do still have a passion for 60/70s American muscle cars which Hot Wheels can still satisfy.
Any race car or concept cars. Pontiac Banshees are among my favorites. I have several of them.
Sooooooo many great castings from the 70s.
Stagefright
Brown Sugar
And Warpath (AMC AMX2) shown here with some customized restoration work. 
My favorite castings through the years. My first tetanus shot was due to stepping on my Red Baron in 1971. Mountain Dew Stocker is just too cool. And the only casting I actually collect is Way 2 Fast. (Only one version eludes me).
This one Dutch. I just picked up the Temecula Rod Run edition last week so...
Another car that's a favorite if only because it's tied to a great memory, is what I found out was a Matchbox called the Cosmic Blues. It's a muscle car with a HUGE blown motor. My grandma gave it to me when I was really young and I just remember playing with it all the time because it was one of the few I cherished, probably because that motor was so shiny and huge. I wish I knew what happened to it, but it likely ended up in the diecast graveyard known as my sandbox.