Critical Knowledge:

2010 Porsche 911: Three new models join the lineup, including the grand-touring 911 Turbo, track-ready 911 GT3, and the race-ready 911 GT3 RS. The other 911 models are unchanged.

2010 Porsche Boxster: A new lightweight performance-oriented Spyder model-with a minimalist convertible top-joins the lineup. The Boxster and Boxster S are unchanged.

2010 Porsche Cayman: No changes for 2010.

2010 Porsche Cayenne: No changes for 2010, but a diesel model and a hybrid variant are expected to arrive soon. This is the final model year for the current generation, as an all-new Cayenne model will debut for 2011.

2010 Porsche Panamera: All-new for 2010, Porsche's first 4-door sedan debuts with V-8 power and a long list of standard luxury appointments.