The upcoming Audi S8->ke1900 has been caught testing for the first time "completely naked" while cruising in the European Alps. These fresh prototypes reveal all the glory and beauty of the S8 set to be launched at the Frankfurt Motor Show this fall.

As you can see in these spy images, the S8 will feature sportier front bumpers, four chrome exhaust pipes in the back, and bigger brakes for added stopping power. That excess stopping power will be put to good use now that Bentley is working on their new twin-turbo 4.0 liter V8 engine. This new engine will be used for the Continental GT->ke401, but will also be finding its way to the S6->ke1207, S7->ke1687, and, of course, the S8. Once dropped in the S8, this new engine will crank up the luxury sedan's output from the current 444 HP to about 500 HP, all while being 20% more fuel efficient than the V10 it is replacing.

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