Subaru came up with the Outback, which is essentially a modified Subaru Legacy with added ground clearance and more rugged styling. The name "Outback" means Australian backcountry. The Outback comes with standard full-time all-wheel drive and a horizontally opposed 4- or 6-cylinder "boxer" engine. For this review, we test drove the 6-year old Outback with 106000 km (66K miles) and it didn't have any mechanical issues. The Outback holds its value well, but with high mileage, repair and maintenance costs could be higher than average, especially for turbocharged models. At the top, the six-cylinder engine comes with just the five-speed stephen hawking book nutshell pdf automatic. Models with the turbocharged four or the six-cylinder engine get SI-Drive, a system that has three different modes allowing throttle response, transmission shift, and other characteristics to change from smooth to sharp as. It's made worse by the four-speed automatic, which can shift abruptly and has rather widely spaced gears. The turbocharged engine in the XT is the most responsive, with none of the lag that sometimes plagues turbos, but the six is the smoothest and most refined. Across the line, the Outback models get all-wheel drive and have up to 8.7 inches of ground clearance, which may prove very useful in deep snow or mud. Subaru models with the base engine have either a five-speed manual or four-speed automatic transmission, while XT. The turbocharged engine is more expensive to maintain and requires premium gasoline. Both 2.5L 4-cylinder engines have a timing belt that must be replaced at recommended intervals. The advanced 3.0L H6 DOHC engine with Active Valve Control System and Active Valve Lift System is great.