NOT SO long ago, the phrase ‘performance diesel’ would be nothing but a risible contradiction in terms, but these days the upswell of such cars is spooling up quickly, just like the turbos they use to deliver such abundant performance.

It may seem strange that the Japanese are introducing such a model to the medium passenger segment, in particular since they have been relatively uninterested in a market dominated by European players.

Though the Europeans, and more recently the Koreans, have offered many a robust diesel, none (except for the just-announced Skoda Octavia RS TDI) have really had the performance to crow about.

So the Mazda6 diesel is only marginally slower than the 2.5-litre petrol model but kills it for in-gear acceleration, and in fact, according to Mazda, the in-gear acceleration is superior to local homegrown V8s in the fourth-gear 80-120km/h increment.

This is all good and well, but does this oiler really go like greased lightning?

The answer is yes and no… on the launch drive, two models were sampled, one a hatch, the other a wagon. The hatch seemed to be lacking clarity in response to throttle input even in the relatively strong mid-range, and a bit noisier than the wagon sampled, too. We put that down to the low kilometres of the test car and perhaps the lack of time to sort them out properly.

Yet there are no complaints about the way the wagon performed, once it reached the 1800rpm point on the tacho - it’s an almighty rush of unstoppable, turbine-like power right though to around 3500rpm before it tapers off. How this engine revs past this point - which is around its peak power revs - is interesting for a diesel as, unlike many, it feels free-breathing right up to its 4500rpm redline and beyond.

The good news of course is in fuel economy, where an average of 6.3L/100km was achieved in country back-road running, with the occasional corner strafing thrown in - this is an excellent fuel figure for a car of this size driven in these conditions.

The claimed average figure of 5.9L/100km seems entirely achievable, and it is interesting to note that the Six diesel is the most fuel-efficient car Mazda sells here - beating its own diminutive Mazda2.

The 2.2-litre turbo-diesel is very smooth too, its balance shaft obviously working to good effect. You really have to listen hard to pick this as a diesel, too. This attribute can be put down to good sound deadening in some diesels, so that the occupants don’t hear the rattle that passers-by are treated to, but standing outside the Six diesel the characteristic diesel rattle is also very muted.

This engine may not be like a typical diesel in many ways - smooth, refined, quiet and very powerful - but the fact remains that like most diesels it works best when you rely on its thick mid-range torque rather than working the gearbox and revving.

There is such a narrow band of power compared with a petrol engine that it is difficult to make a satisfying lunge at a mountain pass as you might a high-revving petrol-powered car. If you let revs drop below 2000rpm, it’s a canyon of nothing, and if you rev beyond 3500rpm - well, the engine’s willing, but certainly past its prime.

The gearshift, in most circumstances precise and easy to use, is reluctant to find third gear when trying for a lightening quick two-three change.

Around town, you can drive this car around in third gear most of the time, loading it up it like an old manual V8. It is not afraid to lug around - provided you are not in a hurry, this is one of the most satisfying diesels around for tooling around town.

Steering weighting feels a bit inconsistent off-centre and there is not as much feel as there could be but there is not much wrong with the chassis dynamics or grip. This is an enjoyable, entertaining car to drive.

Mazda makes a good, quality interior and the Six is no different. If you wanted to be picky though, it’s a bit like looking at a bloke wearing a fine tuxedo… to look down and see him wearing thongs.

The shiny, brittle plastic of the centre console housing is not cut from the same cloth as the high-grade stuff fitted to dash and doors. Despite the large number of panel joins in the plastic trim, Mazda has made it all line up and finished it off well.

The switchgear and instruments are all really simple to use and easy to see, with only the controls for the trip computer, mounted on the steering, hard to find for the uninitiated.

The Mazda’s interior is spacious and comfortable, although it feels as if you are parked up in the corner of the cabin when you first get behind the wheel.

Plenty of adjustments to the seat (power adjustment in the hatch manual adjustment in the wagon) and steering wheel means that it’s not hard to find a comfortable driving position in the supportive bucket seat and the vision out to the front and sides is good. Rear and rear quarter vision are not especially good in the hatch, but at least it has parking sensors fitted for when reversing.

The rear seat is a little flat but the back has plenty of head and legroom. The 60/40-split bench has quick-release levers in the load area to drop down the seats to present a flat load floor.

The wagon’s cargo blind/cargo barrier net is a work of art, with a height adjustment for the cargo blind and a retractable section when you lift the tailgate, but it’s bulky.

Mazda’s new diesel is a very refined engine with a fine compromise of thrift and power, but pitching it as a performance diesel is placing an expectation on the diesel that its powerband is not able to live up to.