Last week’s article was about the soon-to-be-introduced tax reduction for diesel passenger cars. But assuming ceteris paribus on the price front, is there any difference between driving a car with a diesel engine and one with a petrol engine?

The case for petrol-engined cars

Performance

Petrol engines are generally quiet and smooth, more responsive, and have faster revving and better acceleration response than diesel engines. They also usually give more horsepower for any given size of engine. The newer diesel cars may not lose out much in this department, but petrol engines undoubtedly offer better refinement.

Diesel engines have always been noisy and, while the current crop of high-tech diesels are much better in this regard, there is still some clatter when cold or at idle. None can rival a petrol engine for smoothness and noise suppression.

Cost

Diesel cars may have lower fuel consumption, but they are usually more expensive than petrol cars to begin with. The diesel option, particularly a turbo-diesel one, can add up substantially because the diesel engine has more costly requirements in design and building stages.

In terms of upkeep, diesel models normally require more frequent engine oil and filter changes, and in many cases the service parts are more expensive than their petrol equivalents. An added cost in diesel maintenance is a fuel system service, which involves rebuilding the injectors and recalibrating the injector pump.

The case for diesel-engine cars

Performance

Almost all new diesel cars are turbo-charged, which gives them rather decent performance. A diesel engine is more easily turbocharged than a petrol engine as it has no fuel in the cylinder. Diesel engines have higher torque than petrol engines, which means that a diesel engine can pull a heavy load easier than a petrol engine. Diesel engines are built relatively stronger and heavier.

Diesel engines don’t need an ignition system, so they use glow plugs rather than spark plugs which generally need to be changed every two years or so.

Cost

Diesel engines have better fuel-efficiency compared with petrol as they have a higher compression ratio. A given quantity of diesel has more energy than the same amount of petrol, so for any given distance, diesel cars will use less fuel than petrol ones. Diesel is usually cheaper than petrol, so that means absolute dollar savings every time you fill up the tank.

There is also a smaller “environmental” cost, as diesel cars emit less carbon dioxide, which means they pollute less because they use less fuel than petrol cars.