UK-based specialty carmaker GTM is working on a rival to challenge current heir to the ultralight throne, the Ariel Atom. It's the GTM 40TR, projected to excel in feats of quickness (zero to 60 mph in under four seconds) via the the Honda Civic Type R's 220 hp, 2.0-liter four. Top speed should be over 150 mph. The company's also developing a biofuel version for a possible race series that promotes fuel efficiency in motorsports. Guilt-free track day? That's a fine idea.

Ariel Atom killa! GTM 40TR [Autoblog]

Classic Top Gear: The Ariel Atom Will Blow Your Face Off [internal]