2007 Acura RDX

The MDX sport/utility is arguably Acura's biggest critical and sales hit since the original Legend. So why not a smaller, more youth-oriented crossover SUV? Based on Honda's next-generation CR-V platform, the RDX is foreshadowed by the RD-X (adding a hyphen to the names of concepts is a traditional Acura trick) unveiled at the 2002 Detroit auto show. That radical design study would have to be heavily toned down, including such changes as a real dashboard in place of the concept's virtual video game, full-size headlamps, and a more believable roofline with a less-severe angle to the beltline.

Most intriguing in the concept was its powertrain, which could carry into the production model. The RD-X featured a 2.4-liter i-VTEC four (the same engine that makes 200 horsepower in the Accord-based TSX) connected to Honda's Integrated Motor Assist hybrid system and a six-speed manual. In the concept, the IMA powers the rear wheels for a total of 250 horses. The RDX would be the second hybrid Acura, though the first truly targeted as a performance model, following the all-wheel-drive '05 RL replacement, which bows at this fall's Tokyo motor show.

The RD-X concept featured an innovative, flexible interior; some of its layout, flavor, and function should make it into the production version. The RD-X concept's fantasy look also would have to be toned down in order to sell in Japan, where a production version would be badged as a Honda.