Maserati Ghibli Diesel, motoring review: Can Maserati turn itself into a mainstream marque?

Price: £48,830
Engine: 2,987CC, V6 CYLINDERS, 24 VALVES, turbodiesel, 275BHP
Transmission: eight-speed auto gearbox, reare-wheel drive
Performance: 155mph, 0-62 in 6.3 seconds, 47.8mpg, CO2 158g/km

This is the third Maserati in history to be called Ghibli. The other two were rare and rapid coupés, admired by aficionados but probably unknown to most of the people likely to buy this new saloon. These buyers will, so Maserati hopes, be people who have a fear of becoming boring; not for them the safe choice of a German brand, nor even a Jaguar.

This is new territory for the Italian brand, part of a plan to manufacture many more Maseratis including, next year, an SUV. Central to this brand explosion is the four-door saloon you see here. There have been several generations of Maserati Quattroporte ("four-door") saloons over the years, and the most recent is about Jaguar XJ-size, slightly larger than its predecessor. That was done to make room for this new Ghibli, which is based on a shortened Quattroporte platform and is intended to lure buyers away from, say, a BMW 5-Series or Audi A6.

Under its downwardly curving bonnet is a choice of three V6 engines, two twin-turbo petrol units, and Maserati's first diesel. The bodywork that clothes them has an unmistakably Maserati look, with its vertically slatted front grille and curvy rear haunches, but like many new cars it comes across as a touch overwrought with its disparate waves and ridges. I suspect it might date quickly, but the frameless door windows give a neat, crisp definition to the side view.

Inside, too, it's all very busy, laden with leather and lavish fittings. The display screens' graphics are already dated-looking, though, and I never did figure out how to set the windscreen wipers to intermittent.

In the Ghibli S, the top model at £63,415, the 3.0-litre V6 makes a mighty 410bhp. This is channelled through an eight-speed automatic transmission - no manuals for this Maserati - via quite a tightly set differential. It sounds angry, with bluster and burbling from its four exhausts, and given the right road, you can launch the S to 62mph in five seconds and on to 177mph.

This violent power delivery is matched to a firm ride. But it's the sort of sporting flavour that frustrates, because when you are obliged to go gently, the Ghibli feels wooden. There is little deftness to its motion - and certainly not enough to help you swallow the bitter tax pill of a 242g/km CO2 figure.

There is also a non-S version, with 330bhp and a sub-gas-guzzler CO2 score, still very rapid with its 5.6-second 0-62mph time. But the Ghibli most likely to attract buyers is the 275bhp diesel. Whereas the petrol V6s are built by Ferrari, the diesel comes from the less glamorous VM Motori company. It packs a good punch, and sounds at times remarkably like a powerful V8 thanks to sound generators feeding pulses into false exhaust pipes next to the real ones. The result is that rare thing, a tuneful diesel, but authenticity is abandoned for skin-deep values.

Here, too, gentle driving emphasises lethargic responses out of keeping with a Maserati badge. Set in Sport mode, the Ghibli diesel can be entertaining, but it worries me that the car's default state is so far from what a Maserati should be.

The result: a confused personality. I love the idea of an alternative to the obvious Germans, but Maserati needs more courage in its convictions.