Aniruddha Bahal, who posed as an arms dealer to expose an Indian military bribery scandal in 2001, flew to London to receive the prize from rock singer Sting before a 500-strong audience on Wednesday.
Now in its 11th year, the dubious honour is awarded by the Literary Review magazine for the most inept description of sexual intercourse in a novel.
Bahal beat rival nominees including John Updike, Paul Theroux and Paulo Coelho, thanks to a passage from his novel "Bunker 13".
Bahal`s hero says he feels like an "ancient Aryan warlord" after discovering a Swastika shaved into an intimate part of his female companion`s anatomy.
As the temperature between the two rises, Bahal shifts gear in a blur of motoring metaphors.
"She picks up a Bugatti`s momentum. You want her more at a Volkswagen`s steady trot.
"Squeeze the maximum mileage out of your gallon of gas. But she`s eating up the road with all cylinders blazing."
Previous winners include AA Gill, Sebastian Faulks and Melvyn Bragg.