Two midsize luxury sedans: one from Germany and one from Japan. Which is a better choice for carpooling with your coworkers, and more importantly, which is a better driving experience in general? We took the Mercedes-Benz E550 and the Infiniti M56 to the Edmunds test track to find out how much potential they have. Acceleration was tested with 0-60 and quarter-mile tests, while braking was calculated using 60-0. Handling tests included a timed slalom and two trips around a skid pad to generate a lateral acceleration calculation.