SUVs have long had a reputation as oversized gas guzzlers - so are their hybrid versions more environmentally friendly?Lexus led the way with its RX450h. Now in its second generation, the Lexus delivers 299 horsepower. BMW got into the act with the X6, which produces a whopping 485 horsepower, while Porsche's Cayenne Hybrid offers 380 hp. Drive it put the three hybrids through the paces in the Dolomites of northern Italy.