Porsche is a company familiar with making steady progress: witness the enduring appeal and success of its 911. The analogy does come unstuck slightly when the conversation turns to Porsche's Cayenne SUV, however.

Porsche is a company familiar with making steady progress: witness the enduring appeal and success of its 911.

The analogy does come unstuck slightly when the conversation turns to Porsche's Cayenne SUV, however. This was one of those revolutionary products; a gamble for Porsche, it divided opinion and many questioned whether the firm should be in the 4x4 market at all.

Time, and the company's bottom line, has proven that it was. Being Porsche's first attempt it was inevitable that there would be room for improvement. This third generation car is the culmination of many things: a steep learning curve, the desire to improve the car's appearance and maintain the Cayenne's position as a versatile off-roader and sporting car on road.

Long story short, it's job done for this 2010 model Cayenne. Visually the car is now more Porsche-like in appearance. Sounds funny, but its streamline profile, less aggressive nose and wider stance bring it closer in line with the 911 and shares more visual clues with the wider Porsche line-up.

The big strides have occurred under the skin. Not only does the Cayenne now look more like a conventional Porsche, it drives like one too. Chalk this up to a 100-odd kilo weight loss programme and a thorough suspension, transmission and steering refresh.

A clever air suspension system graces the flagship Turbo model and is option on all bar the lead-in V6 petrol, diesel and hybrid variants. It works exceptionally well, affording the car a sense of agility more appropriate to a premium saloon than a chunky SUV. Options include a clever torque vectoring all-wheel drive system and the ability to disengage the anti-roll bars to further enhance the car's performance on and off-road.

And yes, you did read that right - Porsche will now sell you a hybrid Cayenne. In keeping with the its sister car, Volkswagen's Touareg, the hybrid follows Toyota's Prius and allows electric-only running along with petrol (in this case a 3.0-litre supercharged V6) only and a combination of the two power sources for that extra overtaking surge, for example

Apart from keeping the green-tinged critics happy, this Cayenne S Hybrid demonstrates a pleasingly Porsche-like turn of speed on road and is capable of modest rough terrain running, although it does without the fancy, high-tech all-wheel drive system of its petrol V8 relatives. The hybrid's 193g/km CO2 rating is certainly appealing,as is its 34.4mpg combined economy figure. It'll keep the Porsche faithful happy though, as it'll sprint to 62mph in a rapid 6.5 seconds, reinforcing Porsche's assertion that the hybrid offers petrol V8 performance plus V6 levels of economy.

Diesel aside, although another sub-200g/km CO2 Cayenne, it's the aforementioned petrol V8s that remain the mainstay of the range. Even these haven't escaped the environmental clean-up, however. Economy is up and CO2 levels are down. A case in point is the 500 horsepower Turbo model, which boasts previous generation petrol V6 CO2 levels, coming in at a respectable 270g/km.

Part of this is down to a thorough engine and powertrain overhaul, which has resulted in considerable efficiencies. There's also a new eight-speed auto gearbox (shared with the non-turbo V8 and the hybrid), plus a stop-start system, which proves unobtrusive but effective around town.

With all this talk of economy and CO2 savings it's easy to lose sight of the Cayenne's core appeal. A few minutes behind the wheel soon puts that right, and even before turning the key the presence of an all-new interior modelled on Porsche's Panamera reinforces the German firm's increased focus on cabin quality.

Offering the best of everything, the Cayenne Turbo delivers an impressive blend of refinement, comfort, practicality and, unsurprisingly, performance.

PORSCHE CAYENNE TURBO

Price: Porsche Cayenne Turbo, from �81,589 on the road. Range from �41,404.

Engine: 4.8-litre V8 turbo petrol unit developing 500bhp.

Transmission: 8-speed automatic transmission as standard, driving all four wheels.

Performance: Maximum speed 172mph, 0-62mph 4.7 seconds.

Economy: 24.6mpg.

CO2 Rating: 270g/km.