And while the Porsche 911 Carrera isn???t short of good standard features ??? including the brilliant Bose audio system incorporated into both models ??? for a model that will cost about $250,000 (base) and $285,000 (S) once on-road charges are added, you???d think features such as tyre pressure monitoring ($1590), parking sensors both front and rear ($890), and a sportier-sounding exhaust system