Motoring editor Andy Russell knows what he'll treat himself to if his lottery numbers come up...

When my lottery numbers come up – I keep being told to look on the bright side of life – I shall buy a holiday home in France's Loire Valley where I can flit away to for odds weeks and chill out.

And now I have the next step of my plan for I have found the car I will drive there in – the new BMW 6 Series Gran Coupe, a true grand tourer that gobbles up the miles effortlessly and luxuriously – a sporty four-door coupe with the comfort of an executive saloon.

Sleek and desirable… it's got everything – prestige, performance and pure panache.

The Gran Coupe is the third model in the 6 Series range, alongside the recently-relaunched two-door Coupe and Convertible, but is 113mm longer – all between the front and back wheels – to make it the most spacious and practical.

It makes a big impression with its lithe lines giving it an athletic stance and flared wheelarches emphasising its muscular look. From the front and side, with the aluminium doors housing long frameless windows, it looks fabulous but I'm not sure about the backend which reminds me of Volkswagen's Passat CC – nothing wrong with but it didn't shout BMW to me – and that's the view most others car on the road are going to see as the Gran Coupe disappears into the distance.

There are three TwinPower Turbo engines, all with a slick eight-speed sports automatic transmission – 320hp 3.0-litre straight six-cylinder and 450hp 4.4-litre V8 petrol but 80pc of Gran Coupes will pack the excellent 313hp 3.0-litre, straight six turbo diesel and it's easy to see why. Just look at the figures – a back-shoving, ballistic 630 Newton metres of torque from 1,500 to 2,400rpm, 5.4 seconds from zero to 62mph, top speed limited to an academic 155mph yet it can return around 50mpg and its emissions are on a par with an automatic 1.6-litre petrol Ford Focus.

Still not impressed… well drive it and you will be. This magnificent turbo diesel is so flexible, refined and near-silent until you wind it up when it lets rip a throaty exhaust note that gives you goosebumps. Running around saw MPG in the high 30s while a longer, gentle journey pushed it to mid 40s.

BMW is acclaimed for building, well-balanced, fine-driving cars with rear-wheel drive and the Gran Coupe is one of the best, especially if you pay �3,400 extra for Adaptive Drive which allows you to electronically tailor the damping set-up – firm for sporty driving to reduce floatiness over undulating roads or more comfort-oriented for soaking up slow bumpy roads – as well as reducing body roll through corners.

How it all works is beyond me but it's impressive. The Gran Coupe doesn't feel big on twisty roads with nimble responses and flat, confident fast cornering. Even with sport suspension and bigger optional 20in wheels with low-profile tyres the ride on poor roads remained generally supple, unlike the bone-jarring brutality of some M Sport models, although it was caught out by a couple of sunken drain covers.

As standard you can adjust the response of gearbox, steering, throttle and stability control with Eco Pro, Comfort, Sport and Sport+ settings. You decide how you want to drive it and let the Gran Coupe get on with it.

Inside the sumptuous cabin, there's five seat belts but it is effectively a four-seater with deep sculpted outer back seats but I wouldn't want to be perched in the middle, straddling a huge central hump and all the rear controls for the heating a ventilation system. Legroom is good enough for adults to stretch out for long journeys and tall adults will find headroom adequate.

While I wasn't totally won over by the rear-end styling, it does conceal a huge 460-litre boot which goes back a long way but while access is wide, it's also shallow and there is some wheelarch intrusion. Even so, the Gran Coupe will take a load of luggage especially with some soft bags. It can also accommodate two golf bags as well as four people... or a few cases of wine on my trip back from the Loire Valley vineyards. And, not that you're likely to load such a car to the gunnels, rear seat backs split 60/40 and fold flat with a flap between the rear seats for long time items such as skis… won't need those in the Loire Valley!

The fascia is classic BMW, fuss-free, uncluttered, big dials and no-nonsense, quality controls – it's good to look at and use with most major functions controlled through the intuitive iControl knob between the front seats through a large display screen. The cabin is exquisitely finished – as you would expect of a car starting at more than �60,000 – and among the �16,000 of options on my test car was the �1,000 leather-covered instrument panel with contrast stitching – another �195! The anthracite Alcantara headlining at �865 made the cabin dark with the black leather and trim so the �945 electric glass sunroof is a must.

Available in SE and M Sport, the Gran Coupe is well kitted out as standard but, delve into the lengthy options list and you can hike the price severely – for many owners that is part of the pleasure.

Take the Gran Coupe and personalise it to your tastes and it's as good as you're going to get in a luxurious, long-legged, mile-muncher. Now where is that winning lottery ticket?