Arias Pistons 12.5:1 Compression 82mm Bore Honda B-series on 2040-parts.com

2010 BMW X6 M: Fast and fun--whatever the heck it is

Barreling around the racetrack, there's little lean entering the corners, plenty of thrust on exit and a monster amount of grip everywhere, and if it feels taxed at all, it's ever so briefly as the nose aims left and up from turn five for the steep climb out of the esses. Road Atlanta is plain ol' fast, and the BMW X6 M does well to keep pace, spilling gobs of power all over the track, blazing down the long back straight to nearly 140 mph, maneuvering like no two-and-half-ton pile of metal should. It's exhilarating stuff, to be sure, only we're left asking very many questions, and all of them are: Why?

Concept Car of the Week: Citroën Karin (1980)

With the 1980 Paris Motor show approaching and no new model to unveil, Citroën needed something to wow the crowds on its home turf. Trevor Fiore – who followed Robert Opron as the head of Citroën Design for a short time – gave the go-ahead for an innovative concept starting from a blank sheet of paper. The final concept was named Karin, and it was nothing short of breathtaking.

Mercedes Marco Polo (2014): first pics of Merc's camper van

By Tim Pollard First Official Pictures 10 July 2014 10:51 Mercedes has unveiled its answer to the VW California camper van: the new V-class-derived Marco Polo bijou home on wheels. As the exploratory name suggests, the Mercedes Marco Polo is for adventurous types who want to take their home with them on outdoor trips and camping holidays. Not sure we'd take one from Venice to the Far East though, like its namesake...