Encased under glass and lit up like a museum piece, Audi’s ten-cylinder totem to humen ingenuity looks as if it should be accompanied by a soft-spoken docent to narrate its very existence: At 610 horsepower, this naturally aspirated 5.2-liter V-10 is the most powerful engine ever put into production by Audi. it revs 20 percent quicker than its predecessor, spinning from idle to its 8500-rpm redline in 0.66 second. Except this naturally aspirated ten-cylinder isn’t a museum piece. It hasn’t been driven to extinction by downsized, turbocharged engines-not yet, at least. It is the World’s Greatest hands-on museum.