The Audi R8 was initially equipped with a 4.2 litre V8 engine. Specifically, it is an all-aluminium alloy 32-valve (four valves per cylinder) petrol engine, utilising Fuel Stratified Injection (FSI), and has a displacement of 4,163 cubic centimetres (254.0 cu in). It develops a motive power output of 309 kilowatts (420 PS; 414 bhp) (Directive 80/1269/EEC), and generates 430 newton metres (317 ft·lbf) of torque, on 98 RON 'Super Unleaded' petrol. It is basically the same engine used in the Audi B7 RS4, but is modified to use dry sump lubrication system. This V8 is a highly reworked, high-revving variant from the existing 4.2 litre V8, but includes cylinder-direct fuel injection (Fuel Stratified Injection), and four valves per cylinder, instead of five (as used on the previous non-FSI variants). It also uses two chain-driven double overhead camshafts (DOHC) per cylinder bank, and utilises variable valve timing for both inlet and exhaust camshafts. The transmission options are either a Lamborghini sourced six-speed manual gearbox with metal gate for the shift lever, or an Audi-developed R tronic gearbox - which is a semi-automatic, without a traditional clutch pedal with automatic gears shifting mode. These options are the same as those available on the Lamborghini Gallardo. A double clutch Direct-Shift Gearbox (DSG), now badged by Audi as S tronic, is not available (as of April 2010). Source Wikipedia

"Its front-mounted four-cylinder in-line engine was bolted directly to the new, pressed-steel frame and had the sensational output of 35 hp (26 kW). The engine speed was regulated between 300 and 1000 rpm by a lever on the steering wheel. The cylinders and cylinder head formed a single unit, and for the first time the crankcase was made of aluminum. The power-to-weight ratio was now only 6.6 kilograms per horsepower, and one year later it fell to just 4.6 kg/hp. The intake valves were no longer controlled automatically, but by camshaft, like the exhaust valves. The car featured a spray-nozzle carburetor, honeycomb radiator, cooling fan, gear-type oil pump, water pump and magneto ignition. Equally new features of the car included a very compact, self-adjusting spring-band clutch, a single gearshift lever moving in a gate to operate the four-speed transmission, and a heavily inclined steering column. The significantly longer wheelbase, wider track and wheels of virtually equal size on both axles gave the car a high level of handling stability. The brakes were matched to the raised engine performance. The Mercedes was fitted with 30 centimeter wide drum brakes on the rear wheels, operated via a linkage by a manual lever. The foot-operated service brake acted on the drive shaft." - (cited from Daimler webpage)