Question: What performs like a BMW 328i, has a top speed of 129 mph yet gets 50 miles to the gallon? The answer is the new BMW 320d, the "d" as in Diesel.

Best Executive Diesel Car of the Year 2000: The new BMW 320d should finally change people's minds about diesels.

A 1.9-liter four-cylinder high-pressure direct-injection turbo diesel lays claim to the highest specific power and torque figures in its class. With 136 bhp and 206 lb-ft of torque at just 1750 rpm, the turbo diesel's pulling power is equal to the potent six-cylinder 328i gasoline engine. Performance is equally impressive, hitting 60 mph in 9.9 seconds with a top speed of 129 mph.

Through a combination of variable intake geometry and a high-pressure turbo designed to build up just the right amount of pressure at the right time, the 320d's has torque that makes for effortless overtaking thrust. The crucial 50-75 mph burst is dispatched in 8.7 seconds, more than four seconds faster than the 318tds and only a second off the 328i's pace.

Those looking for more power will be able to choose the bigger-engined 330d, which uses the 184bhp six-cylinder common-rail engine fitted to the 530d. The 530d is also available in a Touring model.

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Here are some of the technological innovations in the 320d engine: 

• A new radial-piston injection pump that allows high injection pressures of 1350 bar (more than 1700 at the jet itself).
• Much reduced knocking due to a two stage cam. A small volume of fuel is injected to allow the combustion process to start softly and more quietly before the main quantity is delivered.

• A high pressure turbocharger with Variable Nozzle Turbine (VNT) which allows the turbo vanes to adjust position according to engine loading. This ensures high pressure and higher torque at low revs yet maintaining extra power at high engine speeds.
• Four valves per cylinder
• Intercooler
• Reduced friction inside the engine
• Electronically controlled cooling and exhaust gas recirculation (EGR) 
• Additional heater for heating up the coolant after a cold start

BMW has worked hard to eliminate diesel clatter, with heavy under hood insulation and engine shrouding plus the benefits of a two-stage cam, which 'softens' the burning process to reduce noise. The result is impressively quiet and smoke-free, even after a cold start.