Picture the type of car with the least chance of making it through the unprecedented market conditions the motor industry faces, and it might be something like this: an expensive SUV that seats only five and, because there’s no diesel option, likes nothing more than belching out more than 300g/km of CO2 between (frequent) visits to the petrol station.

And, for that final twist, you’d make sure it came from a marque nobody had heard of, just to ensure there was no chance of brand loyalty scoring you a few sales. Welcome to the Infiniti FX50S, which goes on sale next summer at a likely price of £55,000.

Infiniti? You will be forgiven if the name rings no bells because, while the marque has been around for 20 years, it began life in the US and is starting to establish itself in Europe only now. Infiniti is to Nissan what Lexus is to Toy-ota, a standalone luxury brand designed to sell big-ticket products to a public who’d not countenance such cars wearing the badges of their real creators.

There will be three distinct models: the G series, comprising a small saloon and coupé to rival the BMW 3-series; the EX, a mid-sized SUV in the Audi Q5 and Volvo XC60 mould; and the FX (which, perhaps surprisingly, is the one Infiniti reckons will be its biggest seller), a natural rival for the likes of the Porsche Cayenne and BMW X5.

All Infinitis apart from the FX are powered solely by a 320bhp 3.7 litre V6 motor. The FX comes with either the V6 (FX37) or a 390bhp 5 litre V8 (FX50). The FX is also the only model to receive as standard the greatest parking aid since the invention of the rear-view mirror. Using information relayed by cameras at the front, rear and on either side of the car, a central computer builds up a composite bird’s-eye view of the vehicle and displays it on the dashboard.

What this means is that you can in effect look down on yourself as you park, and see anything anywhere on the perimeter of the car that you might be likely to hit. At first it’s slightly disconcerting but soon you’re left wondering how you ever managed without it.

Which is more than I can say for the rest of the car. The FX50S is not a car you need, but it is a car you want. In fact, it’s the ultimate guilty pleasure. Unlike a Porsche Cayenne, which is ugly, and a BMW X5, which is dull, the only place the FX’s looks would fail to stand out would be on the streets of Gotham City.

And, thanks to the big V8, it walks as well as it talks. You can buy new Porsches that don’t accelerate as hard as this (the Cayenne GTS among them), and with a fast-acting seven-speed paddle-shift gearbox as standard, it instinctively knows the best gear for the road you’re on. It’s also a car that can be hustled through corners with surprising haste given its size and weight.

Infiniti’s engineers have done everything in their power in the vain hope of creating an SUV that handles like a sports car, including making the chassis from a stretched version of that fitted to the fantastic Nissan 350Z coupé. There is also an intelligent four-wheel-drive system, electronically adjustable shock absorbers and rear wheels that turn with the steering wheel. We’ve seen active rear steer systems on smaller cars, but on an SUV like this, it’s a first.

The FX is quick, composed and even fun on the right road. It’s probably not quite as capable as a Cayenne, but nor is it far behind.

What it lacks is the finesse you have every right to expect from a car costing this much. The ride seems good on smooth roads, but deteriorates rapidly on bumpy surfaces; the cabin is luxuriously appointed, but lacks class; cruise down the motorway and you’ll never quite escape the wind noise or the rumble of the colossal 21in tyres.

It would be hard to imagine a less suitable time to introduce such a car as the flagship of a new brand, particularly as that involves trying to steal customers from the likes of BMW and Porsche, but the timing will have been decided years ago. Perhaps that’s why Infiniti has kept quiet about how many UK-bound FXs it hopes to sell: if only a few hundred were shifted in the first year, you sense it would not be disappointed.

I’m torn myself. On one hand I was struggling to get on with this kind of car long before it became fashionable to knock them; on the other, if I had to swan around in a 50-grand SUV, I’d probably make it one of these. Not because it’s better than a Porsche or BMW – it’s not – but because its looks and no-pris-oners attitude to the open road would amuse me more. And when the lynch mobs are hard on your heels, it will help to have something to smile about.

Vital statistics

ENGINE 5026cc, V8

POWER 390bhp @ 6500rpm

TORQUE 367 lb ft @ 4400rpm

TRANSMISSION Seven-speed auto

ACCELERATION 0-62mph: 5.8sec

TOP SPEED 155mph

PRICE £55,000 approx

TAX BAND G (£400 for a year)

VERDICT It’s so likeable, you’ll hate yourself

RELEASE DATE Summer 2009

ALSO WORTH CONSIDERING...

Porsche Cayenne GTS £55,250

For: Smooth engine, excellent handling, driving position

Against: Everyone will hate you, looks, thirst

BMW X5 xDrive 48i M Sport £54,620

For: Seats seven, refined, comfortable

Against: A little cumbersome, dull appearance