The BMW X3 M is a compelling vehicle if you're looking for crossover practicality and fantastically potent performance – and the M Competition model is the one to have, boasting an impressive 503 horsepower from its twin-turbocharged 6-cylinder engine. This example also features some great equipment like the Executive and Driving Assistance Pro packages – and it's completely unmodified, which is a nice benefit.  Power comes from a 3.0-liter twin-turbocharged inline-6, rated at 503 horsepower and 479 lb-ft of torque. Output is sent to all four wheels via an 8-speed automatic transmission and BMW's xDrive all-wheel drive system.