There are Liquid Metal Alloys too, inventors claim its 10 times stronger than Carbon-fiber and Lighter too. Also, recent breakthrough in Nano-shaping the Necessary Metals claims to Achieve that Strength and Weight ratio by 10 more times, i.e. 100 times Efficient that Carbon-fiber. Too good to believe. They are planning to use it on Space Rockets and Aeroplanes. My be for future Upgrades.
For now Carbon-fiber or similar (economical) materials seems good choice. And i’ve seen few Car Chassis designs with Complete Fiber only… but with lot of members and connection… Molded in one shot. One such Fiber Chassis is used in Velodrome design… Human Powered Cars.