According to German publication Auto Motor und Sport, Audi will be debuting its V12 TDI-engined R8 at the Detroit motor show (January 19 through 27.)

The R8 V12 TDI comes equipped with the same engine as the Q7 V12 TDI; a 6.0L, 500 bhp and 1,000 Nm turbo diesel engine with direct fuel injection which is based on the Le Mans 24 hour-winning race engine.
Average fuel consumption is less than 10 litres/100 km and complies with the strongest emission regulations due to catalytic converters and urea injection.
The mighty oil-burning unit weighs around 100 kg more than the 4.2L V8, but still accelerates 0.4 secs faster to 100 km/h than the V8 version.
Source: German Car Scene

The R8 V12 TDI comes equipped with the same engine as the Q7 V12 TDI; a 6.0L, 500 bhp and 1,000 Nm turbo diesel engine with direct fuel injection which is based on the Le Mans 24 hour-winning race engine.
Average fuel consumption is less than 10 litres/100 km and complies with the strongest emission regulations due to catalytic converters and urea injection.
The mighty oil-burning unit weighs around 100 kg more than the 4.2L V8, but still accelerates 0.4 secs faster to 100 km/h than the V8 version.
Source: German Car Scene
