Maybe a new car build material: Carbon Fiber Reinforced polymer.
It’s 90% cheaper than normal Carbon Fibre, and 70% as stiff 
It’s also used to build the monocoque of the BMW i3 and i8 and the Airbus A380.
Maybe for later additions. For now, I think the current materials pretty much cover it all. The usage of this new material you talk about is still like 0.00001% of the market, so not worth adding yet.
And the BMW M3 E91/E92 (coupé and sedan/wagon) bonnet is made in CFRP, and the coupé roof the same.
The new M3/M4 uses CFRP for the bonnet, trunk door and roof, the front stabilizer rollbar (I think).