Lying with my cheek to the gravel roadside on the high moors of County Durham, I was frustrated. The underbelly of the Cadillac SRX, stretching away from me into the middle distance, was obviously not designed for anything other than a few gentle forays into the grass. Parts of the exhaust pipe appeared below the chassis and bits of plastic bumper and a bolt-on loop looked rather vulnerable. I wanted to take a dirt track to those distant autumn woods but this SUV simply wasn't up to it. Even the first ten yards of the rain-gullied dirt road would have done serious damage to the dangly bits under this £39,850 luxury 4x4.Cadillac, the prestige wing of General Motors, is launching a full-scale assault on the European motor market. It got its toe back in the UK's door in May with the CTS saloon. Now it plans to blitz the whole of the top end with performance, luxury and SUV vehicles. Its SUV is this SRX - translated that stands for S-series Reconfigurable Crossover. In short, it's a four-wheel drive, road-orientated station wagon, built on the same platform as the CTS but given a little bit of extra ground clearance.So what's it got to boast about? Well, despite limited mud-plugging aspirations, it simply shines on the road. It's faster than any other 4x4 in the price range, it's got a distinctive image, you can get it with seven seats and it has one of the biggest sunroofs I've ever seen on the options list.The SRX comes with a 3.6-litre V6 petrol engine option, but this test car, in range-topping Sport Luxury trim, has the king-of-the-heap 4.6 V8 petrol engine - a thirsty beast which turns out a class-leading 325bhp and 315lb/ft of torque. On paper that translates into a 0-62mph sprint time of just 7.4 seconds and a top speed of 140mph. In reality that's nought to naughty in about the same amount of time as it takes to read this sentence out loud. It does it with an utterly satisfying warbling growl from the tailpipe too, so even without Tchaikovsky on the stunning eight-speaker Bose sound system you've always got a stirring backing track to your acceleration.The power is fed to a full-time four-wheel drive system through an extremely smooth five-speed automatic gearbox which also offers you Driver Shift Control - Cadillac's semi-automatic sequential gearshift. Traction control can be selected or dropped, but why I'm not sure. With it disengaged I dropped a full-power standing start on wet, shiny tarmac and totally failed to get any kind of scrabble from the wheels.What I did get was a big grin as the horizon rushed up to meet me. The steering felt precise, the suspension was firm and the cornering accurate, but that straightline acceleration was tremendous fun. I gave it a wiggle test at speed on an empty patch of road to see how fast the suspension brought it back into line and the whole experience was clean enough to be totally uneventful.So as a road car it's more than adequate, but what about the kit levels? Well, besides the saintly sound system, it also has heated, electrically-adjustable front seats, dual zone climate control with air-conditioning for the back seats too, touch-screen satellite navigation and voice command audio controls. The centre-screen DVD player for back seat passengers adds £1100 to the price. The giant sunroof arrangement costs an extra £1850; it lifts and winds back electrically over the roof to bring a tuft-rustling breeze to front- and second-row passengers.Right back in the boot there's another little roof window with an electric blind. Why? Because there are seats in there too when you need them. It sounds impressive to say the back seats fold and disappear into the floor at the touch of a button, but in reality that's not the case. When they're up, the squabs are on floor level so there's nowhere to dangle your legs. Occupants may get three-point seatbelts to keep them safe, but they'll get friction burns on their ears from their knees rubbing them as they go round corners.Oh, and here's another interesting take on an old issue. Rather than having the steering wheel adjustable for reach, the pedal heights are electrically adjustable on the SRX to suit the length of your legs.Inside it's a strange mix of opulence and tawdriness with plush leather seats let down by cheap-looking injection-moulded plastic hinge covers. A vast acreage of black plastic curves over the dash, punctuated by bits of wood-effect insert. It feels a bit of a letdown on a car costing nearly 40k.Outside, the love-it-or-hate-it looks are polarising. The SRX carries the current corporate Cadillac look with stack-em-high blocks of lights on the front and rear corners, and an angular grille. From the side it looks longer, lower, sleeker and faster than any other SUV I can think of. To my eye, sexy it ain't but distinctive it surely is. Heads turn everywhere you go and if you get one in black there'll be nothing on the road looks as mean, solid or intimidating. A real hit-man's car.It's going to be image and performance that will sell this car rather than practicality or economy, but even then it's got its work cut out. It may be cheaper than many other big-engined offerings from European prestige marques but the Cadillac badge doesn't carry as much kudos this side of the pond as it does in its native US.Residual values of these first-generation imports need questioning too. You can only get the SRX in left-hand drive and with these massive engines at the moment. When right-hand drive and a diesel engine become available at the end of next year, secondhand prices are bound to suffer. In these times of spiralling fuel costs, the appeal of a 20mpg engine in the UK may also be about to run thinner.