On its way out of production, Audi graced the ageing B7 with one last parting piece of performance. The RS4 Cabriolet was announced in late 2007 as a 2008-only model and ripped the top of of Ingolstadt’s signature small super sedan. Like the rest of the A4 Cabriolet production, it was soft-top only, 2-door only configuration, and like the RS4, it was 6-speed manual only. Under the hood lay the same BNS 4.2 32 valve V8; Audi dropped the 5 valve technology for the RS4 application, but gained quite a bit of horsepower in the process. Though the engine shared basic construction with the normal S4 V8, it had a unique crankshaft, connecting rods and pistons, cylinder heads and valvetrain, oil and cooling system, intake and exhaust system, and engine management system. Audi also introduced their Fuel Stratified Injection (FSI) system. The result was 420 high-revving horsepower and enough noise to make Pavarotti jealous.
Although the RS4 Cabriolet shared the revised T3 Torsen setup, Dynamic Ride Control and huge 14″ front brakes as the sedan, Audi’s focus for the model was exclusivity rather than sport. The model was fully loaded with only one option – color – and came to market at a substantial $15,000 premium over the 4-door. Only 300 were sold with a sticker price of about $84,500: