Bolt-eng Valve Rocker Arm on 2040-parts.com

Concept Car of the Week: GM-X Stiletto (1964)

With dreams of flying cars as the ultimate inspiration, General Motors designers in the ‘60s used every trick possible to make their creations appear as though they were floating – long, straight bodies, wheels pushed in and hidden away, large fins and lights that looked like rockets. As William L. Mitchell took the reins of GM Design, he brought a more high-tech approach, with simpler surfaces, a more restrained use of chrome and a general sense of elegant simplicity.

Lamborghini Egoista (2013) first official pictures

Lamborghini's latest birthday present to itself is this: the crazy-looking Egoista concept. The one-off Egoista follows the Veneno and Aventador Anniversario in paying tribute to Lamborghini's 50th year in the supercar business, and is the most radical looking yet – it's so exclusive Lambo isn't even considering putting it up for sale. Is the Egoista just a bodykitted Gallardo?

Audi e-tron Spyder concept

Audi revealed the latest iteration of its e-tron product range in the form of the Spyder concept at the 2010 Paris motor show. The roadster showcases the brand's plug-in hybrid technology cloaked in an emotional two seat package. Measuring 4060mm long, 1810mm wide and 1110mm high, the Spyder is only slightly larger than the electric e-tron concept shown in Detroit earlier this year.