BY DANIEL GARDNER | 14th Nov 2014
The bellowing tailpipes silenced anyone who predicted that the presence of turbochargers would soften the characteristic demonic Maserati sound, but when the car-maker announced the same model would receive a more practical diesel engine, the naysayers reemerged.
Completing the Quattroporte trio is this - the $189,000 plus on-road costs Turbo Diesel.
With 202kW and 600Nm of meat-and-three-veg torque, the 3.0-litre single-turbo V6 is no asthmatic, but can it carry the famous Quattroporte flag with the same righteousness of the middle of the range V6 S and the effervescent V8 GTS flagship?First impressions are good and for a simple reason - other than the four round tailpipes and smaller wheels, the Turbo Diesel is visually indistinguishable from the petrol varieties. The GTS has trapezoidal pipes and 20-inch wheels in place of 19s, but other than that, all the classic Maserati looks and equipment gets carried over.
On the diesel, trademark triple front wing vents, gaping radiator grille and elegant coupe-like roof-line creates the same, immediately recognisable shape.
Inside it’s the same story. Well appointed leather and wood covers much of the cabin giving a feel of quality and comfort without being garish or too try-hard classy and very Italian.
Space is not at a shortage in the cabin and the back seats are almost as luxurious as the front. Long trips with four on-board are made easier with a voluminous 530-litre boot.
But as GoAuto has reported before, the quality and finish of the Quattroporte has never been in question, and what is most interesting about the newest variant is what lies under the bonnet.
Firing up the Turbo Diesel is the first time an unsuspecting driver would discover something is a bit different, as the engine spins up to a low idle with a satisfying and solid diesel thrum.
Engaging first and pulling away is much the same affair as in petrol variants with a super-smooth uptake from the ZF eight-speed automatic transmission and little report from the exhausts.
Around town and at low speeds you would be hard pressed to pick a difference between the diesel and the more thirsty engines, but with more involved driving the diesel starts to get left behind.
Pointing your right toe in the GTS produces a blood-curdling soundtrack, which changes and evolves as if it is alive, but ask a little more of the oil-burning six-cylinder and it returns less of a performance.
There is no doubt that the note produced by the Turbo Diesel is impressive for a compression-ignition engine but it struck us as a little too synthetic and restrained.
Maybe this is because the diesel sound is, in part, artificial. A system of resonators boosts the exhaust note but, more cleverly, the active noise cancellation ignores the portion of sound produced by the exhaust and not only allows it through to the cabin but amplifies it too.
The result is a deeply satisfying drumming rumble, but sadly any pleasant sounds are lost as the road and wind noise drown it out at higher speeds.
With the windows down the single big turbo with variable area nozzles makes no secret it is hiding under the bonnet, with a noticeable whistle over the purposeful diesel gruffness.
Slightly underwhelming soundtrack aside, the diesel donk does perform well and, while acceleration isn’t as scintillating as the mighty V8, it does pull strongly through to the 4500 rpm governor and has plenty of puff left at higher road speeds.
Many manufacturers are opting for twin-turbo applications to reduce turbocharger spinning mass, which in turn reduces undesirable turbo-lag, but despite the Maserati V6 having just one big turbo, lag was surprisingly minimal.
That big turbo does mean a hose-stiffening 1.8bar of boost pressure can be applied to the six cylinders producing a power output that Maserati claims is class-leading.
With 600Nm of torque, negotiating the undulating roads of Northern New South Wales was no trouble for the big Maserati, and summiting each steep climb was executed with ease without having to wring-out the V6.
It certainly doesn’t have the neck-snapping grunt or crackling exhausts of the GTS, but almost all can be forgiven at the fuel bowser. During our somewhat enthusiastic road-test we managed fuel consumption of just 7.7 litres per 100km.
Not bad for a car weighing in at over 1885kg and capable of getting to 100km/h in 6.4 seconds, but with a more sedate driving attitude, Maserati says a figure of 6.9L/100km and 900km on one tank is possible.
Descending steep hills was also of little concern to the Turbo Diesel and even though this variant has forfeited the big cross-drilled composite discs from the petrol range, the ventilated one-piece rotors scrubbed speed with a positive pedal-feel and minimal fade.
With the new engine comes Maserati’s first idle-stop system, which refreshingly is an opt-in system where every other system we have encountered is opt-out.
The fuel saving system can be turned on and off through the on-board computer but - critically - the status is remembered when the ignition is turned off and back on again, but even if you do choose to live with it permanently, it is very unintrusive.
Maserati’s engineers were so concerned about the system not compromising off the mark acceleration, that they engineered a special fluid pressure store into the ZF eight-speed automatic transmission.
The reservoir provides fluid pressure to the transmission as soon as the driver lifts their foot from the brake pedal rather than waiting for the engine to fully start and generate the required pressure.
The result is a seamless pull-away with minimal, almost imperceptible delay.
The rest of the ZF transmission - including ratios - is unchanged from the two other Quattroporte variants. We felt the first and second ratios were just a little short for the gutsy diesel torque, but up in the higher gears the eight-speed auto was sublime.
Under the Quattroporte, the chassis has not changed either and the same confidence inspiring grip afforded by a large footprint and long wheelbase carries over from the petrols. The diesel engine adds just 25kg over the V6 petrol and comes in 15kg lighter than GTS.
Our car had optioned-up 20-inch wheels, which looked the business and didn’t transmit excessive amounts of road noise or vibration but could at times be a little choppy for a large limo. The standard 19-inch offering would likely give a better ride but Maserati says a majority of customers will favour bigger hoops.
The simple variable drive dynamics selection is the same too and allows easy selection of various sporty functions.
Ride settings can be firmed up with the suspension button, which also eliminated a curious juddering from the steering over uneven road surfaces.
The sport button increased the engine torque output and boosted the exhaust volume at lower revs as well as increasing throttle sensitivity.
An I.C.E. button reduced torque and system sensitivity for a smoother ride for use about town and the M button allowed manual selection of gears through the column mounted paddle shifters.
There is no doubt the Maserati Quattroporte Turbo Diesel is every bit a Maserati with pin-sharp styling, plush interior fit out and design and a rewarding chassis despite its size, but impressively frugal diesel engine leaves one vital element out of the equation.
We are certain the most affordable Quattroporte has what it takes to do battle with the diesel powered prestige coupe/sedan competition such as the BMW 6 Series Gran Coupe and Porsche Panamera, but with a bit more of a voice the Turbo Diesel could have really stuck its trident in.