 The only changes were very subtle, comprising a single horizontal bar on the somewhat enlarged radiator grille, which had been steadily increased in size from the 405 to the 406 through to the 407, plus two exhaust pipes instead of one at the rear.However, under the bonnet of the 407 was not the old BMW-derived six-cylinder engine that was now inadequate for Bristols to be able to compete in performance with other British makes of luxury car.Replacing the old six-cylinder engine was a Chrysler V8, built in Canada, fitted with a new camshaft and mechanical tappets (lifters) of Bristol design.