The answer lies on the engine. This 3-liter inline-6 with variable twin-turbocharger was first introduced to 535d in the form of 272 horsepower, but later improved to 286 horsepower at 4400 rpm. The clever combination of two different size turbos – the smaller one for low rpm and the larger one for high rpm – and the smooth transition between the two turbos enable an almost instantaneous response and virtually free of turbo lag. The engine is so efficient, just 20hp short of the petrol 335i and it returns superior fuel consumption at 37.7 mpg. More telling is the tremendous torque curve which peaks at 428 lbft from 1750 rpm to 2250 rpm. No other 6-cylinder turbo diesel engines are so punchy!

With so much torque, no wonder the 335d Coupe feels faster than its petrol brother in real world. We used to think 335i effortlessly quick, but 335d sets new standard again. So effortless that there is no point to insist a manual gearbox. The 6-speed automatic is both silky smooth and responsive thus is a perfect companion with the diesel engine. The engine itself is also very refined. Apart from a slight diesel-like vibration at cold startup, you are not easy to tell whether it is a diesel or a petrol engine.

Compare with an automatic 335i, the 335d gained only 30kg over its front axle. This makes the steering heavier and the ride a little firmer at low speed, but otherwise it handles and rides as brilliantly as 335i.

Back to our question, is 335d better than 335i ? that depends on your preference. If you prefer effortless driving style, 335d will be the better choice. If you prefer to play with engine rev and gearshift and enjoy the best possible ride and handling, then 335i will be the ultimate choice.