C & D breaks down the engine choices into " the good, the bad and the ugly," with the good going to the 4.2-liter TDI (326 HP and 561 lb.-ft. of torque), the bad being the 3-liter V6 (233 HP and 369 lb-ft. of twist) and the ugly as the twin-turbo V12 found in the R10 racecar. The latter is making close to 500 HP and a kidney-punishing 738 pound-feet of torque, which because of its high weight and intricacies would make it a poor choice.
Notable absent from the mag's lineup is the 5-liter V10 found in the Touareg that produces 308 HP and 550 lb-ft. of stump-destroying torque, but considering that the 4.2-liter TDI makes more power and more low-end grunt, we understand why it was left out of the mix.
If Car and Driver's sources are to be believed, expect the TDI R8 to come to market in 2009. That, along with a rumored Targa version supposedly due that same year, would cause the R8 line to swell beyond feasibility. Time will tell, but we like what we hear so far.
[Source: Car and Driver via the German Car Blog]