GM had magnesium wheels as an option on C5 Corvettes. Check into them though and I believe you will find that it isn't worth the cost. I remember reading on motorcycles that it was recommended that you have you Mag wheels x-rayed to confirm no cracking.
GM has been way ahead on materials. Just never got credit for it. GM had aluminum hoods and liftgates on the SUVs which were eliminated simply due to the cost.
GM invented super plastic forming aluminum and used it to put a highly formed decklids on the STS and hatch on the Malibu Maxx.
GM had the one of the first carbon fiber hoods in the industry on the C5 Corvette LeMans special edition. (I managed the team the did that one
)
Carbon fenders, floors and other trim on the C6 Z06 (did those too
)
Aluminum frame on the C6 Z06 (yep did that)
Magnesium cross member C6 Z06
GM is there in the forefront and has been for years. Just never got the credit for it. Not sure why. Bad marketing? Just being number 1? Never understood it.