The new Optra Magnum comes, quite literally, sporting another face-lift – its third in what feels like practically as many years. Only this time, that's not all, it also has a trick up its sleeve – a very powerful trick actually.

The Optra Magnum has more than just a new face, it has a new heart as well – a market leading diesel heart at that. What GM has managed to do with this 2.0 litre commonrail direct injection (TCDi as they call it) diesel is astounding. This is a diesel that actually likes to rev – an oxymoron, until now!

The heart and soul of this car is the engine – one that feels a lot more powerful than 2.0 litres. It's smooth and rev happy, it even sounds muscular, but most of all, it's as powerful as its name suggests. I never thought I'd say this about a diesel motor, at least not yet, but it is fun to drive.

Like most diesels, it may red line at only 4500rpm. Like most turbocharged diesels, it may have considerable lag under 2000rpm – in this case, perhaps even more so. But keep it in its power band and, very unlike a diesel, it revs smoothly, and without running out of steam, all the way to the red line.

The surge of power continues through the gears till you're on the wrong side of the speedometer doing three digit speeds and then some. It seems completely effortless, at least in a straight line. What's more, the engine serves up equal helpings of power and refinement – it has a balance shaft to helps eliminate vibration, which it does fairly successfully. A counter rotating balance shaft is a trick used in the past by high capacity four cylinder petrol engines as well to aid refinement.