It's a strange experience for anyone brought up on a traditional diet of Porsche road cars. Sitting in the latest version of the Panamera you have four doors giving access to spacious and comfortable front and back seats. There's a reasonably sized cargo area and it's at the back because there's an engine under the bonnet at the front, and on this occasion, it's a diesel engine at that.It's a long way and more than twenty years from my first experience in a 911, ducking and weaving across Dartmoor in a rear-engined, 2+2-seat, two-door Carrera. But it's an exciting development.Of course we've had the Panamera since 2009 so the concept of a four-door Porsche coupé is no longer such an eye-popper, but the car has proved to be more than just an addition to the company's range of vehicles. It's also turned out to be a useful test bed for new real-world technology.For example, none of the street-fighter sportscars are sullied by oil-burning engines like the one in this test car, but here in the world of four-door motoring it can be tried in the court of public opinion without causing outrage. The same will be true of the plug-in hybrid-engined version we also hope to test before too long.This diesel test car is the second generation Panamera, although the changes from the previous version are a subtle evolution rather than a violent revolution.The engine is a three-litre V6 turbo diesel, milling 247bhp into the tarmac through the rear wheels. It's fed through an eight-speed Tiptronic S sequential automatic gearbox that can either do all the cog-work for you so seamlessly as to be almost imperceptible, or allow you to shuffle through the selection at your preferred pace with paddles under the steering wheel or short-shift nudges on the stick.In comparison to some Porsches, this engine may seem a bit underpowered, but the high torque gives it some deep-biting punch. Look at the figures. It has a top speed of 151mph, it will accelerate through 62mph in 6.4 seconds (almost identical to the 307bhp 3.6-litre V6 petrol Panamera) and yet it will turn up average fuel consumption of around 34mpg. It has a stop/start engine to save on fuel and emissions, and the gearbox can disengage on downhills to allow you to coast without the constraint of engine-braking.The Panamera Diesel is taking us rapidly down the road away from established compromise.Despite the ongoing debate over its looks, I personally think it's just marvellous. The front end is long, low and sleek, the big wheels dominate the lightly sculpted flanks, and the tail end is a combination of a rounded corporate Porsche rump and muscular bulges around the haunches. It's always been sleek, but now, the facelift has sharpened up its image a little, and there's no doubt it's now displaying, clearer than ever, all the indicators of performance.Bigger air intakes at the front, redesigned lights, more of a sweep on the side windows and a new tailgate and back section with a bigger area of glass make up the main changes. The pop-up rear spoiler's a bit wider too.Indoors there is genuinely enough space for four big blokes to travel in comfort without polishing their knees or heads on the upholstery. Under the power-lift boot, there's a fairly big cargo hold, compromised mainly by the steep rake of a back end that’s more defined by and dedicated to aerodynamics than load-lugging capacity.Firing up the Panamera Diesel and heading out onto the road takes you into a new and interesting world. That longer wheelbase gives the car the GT feel. It's a true continent-crossing cruiser with great straightline stability, pliability on all types of road, and all the performance you need to overtake and shrug yourself free of the lesser mortals who are going about their daily grind.The list of techy stuff is vast on this car, but the choice of settings for the throttle response, steering resistance and automatic gear shift are great fun to pick and mix. Changing the firmness of the adaptive air suspension (a £2379 extra) also brings some serious and useful changes to the Panamera's character.The longer you play with a car like this, the more it becomes clear why there are so many settings and options to play with. It's a truly multi-faceted, split-personality car which, setting aside its basic £62,000 price tag (£81,000 with all the extras on this one), could be a useful vehicle for everything from the everyday commute to the Big Adventure.If I were choosing a car to drive down to Italy and back, the Panamera Diesel would be close to the top of the list. It's economical enough to live with, it's quick enough to eat up the miles at anyone's speed limit and it's agile enough to make the prettier roads a joy. It's comfortable enough for a day's hard graft at the wheel, it's big enough to take chums and make chums, it's tremendous fun to drive and it's just very, very cool to be seen in. Engine 2967cc, 6 cylinders Power 250bhp Transmission 8-speed automatic Fuel/CO2 44.8mpg / 166g/km Acceleration 0-62mph: 6.4 seconds Top speed 151mph Price £62,922 Details correct at publication date
