Their quirky product line looked good but, when strapped in behind the wheel, even the sportiest models seemed about as dry and flaky as a loaf of stale baguette.

Yep, the Lion's pride was proving to be all sass and zero substance.

Then, just as we had prepared ourselves to write this French marquee off to the annals of mediocrity, they dug deep and shocked the world with the RCZ, a mesmerising sports coupé that drove as well as its avant-garde sheet metal suggested.

Indeed, fitted with the 1.6-litre turbocharged petrol engine I experienced last year, here was a car that could give the Audi TT a proper run for its class-ruling money.

Well now they have more to pique their interest because Peugeot has gone against the sports car rulebook by shoehorning a diesel lump inside the RCZ's engine bay.

It seems like an odd pairing but considering how well the Devil's Fuel has performed at the Le Mans 24-Hour in recent years, not undeserved.

Unfortunately, whereas the race-winning 908 LMP1 car broils and whooshes to the song of a multi-cylinder monster, the civilized RCZ HDI has to make do with a comparatively pedestrian 2.0-litre turbodiesel. Admittedly it is a wonderful piece of oil-burning kit but here it just seems out of place.

For even though this direct-injection unit whacks out a phenomenal amount of midrange punch, it starts to feel very tight-chested at higher revs.

So instead of taking great relish in chasing the rev limiter through every gear, you find yourself short-shifting and riding along on a big wave of lazy torque.

Effective, yes. But exciting?

Absolutely not! In fact I felt more enthralled in the 308 GTI. Compounding the dull factor is the complete lack of soundtrack. The petrol-powered RCZ, through the wonders of a sonic resonator feeding good vibrations into the cabin, sounds brilliant. With the HDI all you get is a muffled drone that tricks you into believing you're piloting a low-riding mommy mobile.

This is a pity because, as we know, the RCZ is a car that loves being driven with gusto.

It has a great chassis. There is plenty of idiot-proof traction. That reasonably well-weighted steering encourages you to attack corners with all the blind enthusiasm of Anthony Davidson.

But here - paired to this seemingly characterless powerplant with its six-speed manual gearbox that never seems to have the right ratio at hand - all these traits feel wasted; you know, like giving a Playboy Mansion pass to a god-fearing do-gooder.

On some level I imagine the RCZ HDI might make sense to Parkhurst poseurs looking to lower their carbon footprint or travelling sales reps hell-bent on fusing fashion with fuel-sipping frugality.

Other than that, I really cannot see the point of its existence. So, to summarise. Good engine. Wrong car. Stick to one of the two petrol models. I promise, you won't be sorry.

The Specs:

Peugeot RCZ HDI

Engine: 1997cc four-cylinder turbodiesel

Power: 120kW at 3750rpm

Torque: 340Nm at 2000rpm

Top speed: 220km/h

0-100km/h: 8.2 seconds

Fuel consumption: 5.3l/100km (claimed combined) 9.6l/100km (achieved combined)

CO2: 139g/km

Pricing: R366500

We like:

Devilishly handsome

Generous level of equipment

Knows how to handle the curves

We don't like:

HDI engine doesn't suit the car

Lacklustre soundtrack

Interior ergonomics a little fussy