The updated 641 design was overseen by former McLaren designer Steve Nichols after Barnard left Ferrari to join the Benetton team, once the car's development was complete. The car was powered by a 3.5-litre V12 engine, first with the type 036, and later in San Marino with the updated 037. The V12 was rated at 680 bhp (507 kW; 689 PS), only slightly down on the 690 bhp (515 kW; 700 PS) Honda V10 engines used by McLaren, but not as flexible or as good at delivering power out of slow corners as the Honda, the Renault V10 engine used by Williams or the Ford-Cosworth HB V8 used by Benetton.