For my birthday recently, my daughter bought me a new Hot Wheels car (along with a load of other things) and the first thing that struck me was that it was predominately plastic. The body and interior were all plastic, the wheels and the suspension. Just the lightweight cast chassis was made of metal and the axles. Hot Wheels cars used to be among the heaviest diecast cars around in their class - Husky, Matchbox, Whizzwheels and Superfast never came close to the solid, weighty models. The extra weight always made them the best runners on the track and enabled them to hold onto tighter corners and loops.
Besides their sturdy construction, it was the Spectraflame colours that always attracted me - the wonderfully vibrant cherry reds, magentas and antifreeze greens always outshone the more staid and conventional Superfast cars.
Decades later, the classic Redlines still command good prices on the aftermarket, even for really beat up examples, although occaisonally bargains can still be found.
I'm working my way through the early catalogue to try and get as many of the original 'Sweet Sixteen' release and the subsequent years more exotic examples, such as the awesome Noodlehead, Bugeye, Peeping Bomb and the three 'T's - Torero, Twinmill and Turbofire!