So little to bring it to perfection and Maserati's Quattroporte now has a chassis that does justice to its naturally-aspirated 4.2-litre V8. The latest evolution, the £86,400 Sport GT S, is a tauter, more responsive, more refined and better-braking flagship for the company's successful high-performance luxury saloon range.Yet, while the improvements are significant, the changes are minimal, paying tribute to its initial excellence. The GT S sits 10mm lower at the front and 25mm lower at the rear than the other models. The effect this has on the car's image is astounding, and the darkened mesh radiator looks as though it can now scoop up anything in its path and spit it out without hesitation.The threatening stance of the vehicle on its 20" wheels is given an edge by continuing the dark treatment on the side window trims, and twin double exhaust pipes, while body-coloured doorhandles remove the remaining detail distractions and allow the eye to focus on the body lines which clearly identify the car from any angle.Exciting panel sculpture is normally the reserve of smaller sporting models and too often designers fail to direct the energy of their lines on larger vehicles, allowing them to meander off course and disappear in a weak dilution. Not so in the Quattroporte, where every millimetre of surface panelling conveys the energy of the car and at every angle the falling light flexes its toned muscles to display a body that is athletic, yet sinister in its now lower stance.This teasing introduction is the first indication that this model has worked out. And indeed it has; no Skyhook suspension choices here - just the one set-up that is 25% stiffer than the Sport GT with a lower centre of gravity to make the most of the car's near-perfect weight distribution.While the 400bhp engine retains its 4244cc capacity, the unit has a wet sump, new inlet geometry, modified pistons and redesigned cylinder heads. Main advantages are increased torque and lower fuel consumption, while drive is transferred to the rear wheels via a new six-speed automatic transmission developed by ZF.In raw terms, the car sees 62mph from rest in 5.6 seconds with a potential top speed of 169mph. And yet, while you are aware of its performance and its size, everything about it is so controlled and non-aggressive. Clearing the early morning Modena traffic and heading north towards Milan on the autostrada, the car simply ate the distance, the gearbox slicing through the ratios with the utmost finesse.Applying the right foot a little more heavily brought a supportive burble from the exhaust, offering encouragement to keep it planted, but at no time intruding into the ambience of the cabin.Even kickdown on the throttle pedal to select a lower gear brings a rapid yet refined response and the ratios blend with each other rather than noticeably step. For those who wish to challenge the speed and smoothness of the automatic, manual selection is on offer from either the gear select lever or the paddles behind the steering wheel, sensibly fixed to the column rather than allowed to rotate with the wheel.Off the main motorways, and towards the lakes of northern Italy, the car came into its own, ably demonstrating its new-found assets. Taking to the mountainous roads over Monte Baldo to the east of Lake Garda, the quality of the automatic gearchange and overall balance and precision of the car demonstrated the significance of the advancements on this latest GT S model. The car's responses are more integrated, more communicative, yet its refinement remains.The dominant feature is its performance edge and the driver satisfaction this returns, with the revs at times stretching to 7200rpm between changes. Engine braking on downhill stretches is well maintained while new, more powerful front brakes offer extremely confident stopping power.These 6-piston Brembo units feature an innovative construction with the hub collar for the discs cast in aluminium and the braking band, against which the pads close, retained in cast iron. Despite being bigger than those on the Sport GT, their weight is unchanged and there is no distortion with resulting vibrations as the disc gets hot under continuous heavy braking.While the interior offers the expected luxury, it also takes account of the sporting nature of the car with figure-hugging front seats inset with gripping alcantara while control panel insets feature carbon fibre trim with aluminium threads. High end detailing includes electronic operation of the door handles, near silent movement of the electric windows, soft damping on the glove compartment door and grab handles, and chrome bezels on the switch insets.While the Automatic and Duoselect models competently established the Quattroporte range, the new Sport GT S elevates it to a most desirable level and makes a significant contribution to classing Maserati as "one of" the car manufacturers from Modena, rather than "the other one". Engine 4691 cc, 8 cylinders Power 440 bhp @rpm Torque ib/ft @rpm Transmission 6 speed semi-auto Fuel/CO2 18 mpg / 365 g/km Acceleration 0-62mph: 5.1sec Top speed 177 mph Price From £93294.00 approx Release date 01/01/2009