Currently at $10,000 on eBay, the X-4 concept car was the “only one ever made — steel experimental car, built on a 2003 Hyundai platform with a 4 cylinder, dual port, fuel injected engine.” Auction page. Click here for first picture in gallery.
The vehicle is remarkably stable, smooth, responsive and drives like a Porsche or similar sports car. Incredibly engineered by an unknown builder and can be driven of speeds up to 85 mph. And, it gets 45 mpg!