It was snowing when we pulled away from the docks at Aberdeen. Dawn was nothing more than a slight bluing of the sky to the east and big wet flakes were being flurried past the floodlights of the lorry park. It was just typical that we should be setting off for a few hundred miles in a soft-topped Mercedes-Benz. I groaned. We turned south.The car was an E350 CDI Cabriolet in entry-level SE trim and with the BlueEfficiency set-up which means it's tuned for maximum efficiency . . . well, the maximum efficiency you can expect from a three-litre turbo diesel engine. Snuggled down in the heated leather seats, we kept what's known as the acoustic soft top firmly up all the way to our breakfast stop. Thick and insulated it was taut and quiet as we made our way sedately down the motorway, listening to the Kinks on the CD player and staying out of the slush in the under-used fast lane. I turned the heater on in the glass rear window.Looking out at it over a bacon and egg roll, I felt sure the ice and snow would probably melt off the fabric within the next hour of early morning sun. We'd left the clouds behind and now, at this roadside café, we were under clear blue skies and praying for a chance to make the most of the fresh air.Lounging back with a big, black coffee and gazing at the big, black car through the steam, it was clearly well-proportioned even with the roof up. The four lights scowled out at me from either side of a three-slat grille that was dominated by a massive MB three-point star. A long bonnet ran up to a steeply raked windscreen and the rag-top cockpit was smooth, low and coherently blended into the overall lines of the thing. The dark flanks rose in a low wedge-shape and were dominated by the two massive doors and the wheelarches bulging out over the 17" five double-spoke alloys.It was a layby just before Dundee where we pulled over to wind the roof back. It would have been a sin to go any further in the dark on such a bright day. It took 20 seconds to open up to the sky and it can apparently be done at speeds up to 25mph. No catches, no clips, it all happens automatically in one complex dance of motorised levers, hooks, bracers and body panels.The car appears to partly disassemble itself, stow the floppy bits, then pull itself together again. Wish I could do that to myself with the same improvement in looks. There’s now no sign of the roof at all. It's totally stowed, glass window and everything, in a screened off section in the top of the boot. It doesn't leave much boot space but you might get a standard suitcase tucked in there.Driving across that long road bridge over the glittering Tay, it was clearly a day for a cap and scarf - AIRCAP and AIRSCARF to be precise. AIRCAP is a wind protection set up that not only raises a mesh backdraught shield behind the rear headrests, but also lifts a second deflector about two inches above the upper frame of the windscreen. I'm not certain that it does anything for the look of the car but it certainly does work. What little buffet there was to my head with it down, was gone when it was raised and we could chat in comfort.AIRSCARF is a clever bit of pipework that blows hot air on the back of your neck from below the headrest. It tickles. Perhaps I should have driven a few miles in a fetching little off-the-shoulder number to try it out, but years of ingrained habit meant I preferred to just turn my collar up and pull down my woolly hat as we turned out onto the coast of Fife.The seven-speed automatic gearbox is so smooth and efficient that there's little need to wiggle the stick through the sequential shift option. It does take a moment to decide which cog it wants to give you at junctions though. You see your gap in the traffic flow and stamp on the accelerator to pull out but there's an un-nerving second when nothing happens before it picks up its skirts and dashes out. What can I say? It's not an uncommon experience and you get used to it.Time to introduce my passenger. I'm taking Lucy, my middle daughter, to see St Andrews University and she's already in a good frame of mind for it. It's her first time in an open top car and cruising into the ancient heart of this coastal town in £48,000 worth of car-and-extras seems apt. It's Scotland's oldest and best-respected seat of learning; elegant and sophisticated. Mercedes offers one of the oldest and best-respected seats of driving, and yes, it's elegant and sophisticated.It was Lucy who found her way round the system that combines music, satnav and phone, and her that chose the soundtrack for the trip. I'm glad she did. The engine, although powerful enough to pull the 1.8-tonne car up to 62mph in under seven seconds, did so virtually silently. If part of the joy you get from open-top motoring is listening to trumpeting of exhausts, you're going to be disappointed here. Listen carefully and the numbers 228bhp and 398lb/ft are being little more than whispered to you.As the sage said, nothing in life is perfect. You can either live with it or work around it. And so it is with the E350 Cabriolet. Visibility is not good whether you want to look forwards or backwards. With the roof up the rear window is small but the work around is a reversing camera and parking sensors. Whether the roof’s up or down, the view out the front feels very limited, probably due to a combination of a large rear-view mirror, a low frame on the windscreen, and the techy bits that work the AIRCAP system.People and cargo space is limited too for a car that's a full 4.7 metres long. With the roof up any back-seat adults will be brushing their hair on the roof and polishing their knees on the back of the seats in front. The other thing is a long-term issue with Mercedes-Benz in that much of the equipment I've been extolling the virtues of only come as extra-cost add-ons. The AIRSCARF, satnav, DAB radio, smart brakes, adaptive lights, climate control, electric memory seats, the reversing camera and other things add almost £10,000 to the basic £38,660 price tag.And yet, there is something special you should know. Despite the size and weight of the machine, that big diesel engine has an official combined fuel consumption of over 40mpg which in my book makes it something close to saintly. It's powerful, smooth, good-looking and relatively economical. It's a lot of fun too. What's not to like? I’d like to try out the base model sans accessoires just to see if it really is a viable option, but I like what I’ve seen - and so does Lucy. Engine 2987 cc, 6 cylinders Power 231 bhp @3800 rpm Torque 398 ib/ft @1600 rpm Transmission 7 speed semi-auto Fuel/CO2 40.4 mpg / 185 g/km Acceleration 0-62mph: 6.9sec Top speed 155 mph Price From £39156.00 approx Release date 01/03/2010