The Cadillac SRX is a luxury crossover SUV based on the company's rear wheel drive Sigma automobile platform. The SRX was introduced in the 2004 model year. Engine options include the 4.6 L 320hp Northstar V8 and 260hp High-Feature V6. It comes with a 5-speed automatic transmission, and all-wheel-drive is optional. The SRX has been Cadillac's best selling model in the United States since 2010.