Addictive best describes the Mercedes-Benz GL450's fantastic 335-horsepower, 4.6-liter V8 engine's powerband. This 5,249-pound SUV is a rocket, building velocity at a mind-boggling pace. The seven-speed automatic transmission shifts sublimely under all circumstances, kicking down into the thick of the power with just a moment's hesitation. Plus, it sound great. Of course, fuel economy suffers when the power is exploited. We drove like jerks only part of the time, and still managed just 14.6 mpg, right between the EPA rating of 14 city and 18 highway.