Review of the new Vauxhall Insignia ecoFLEX

With 158bhp and up to 380Nm from its 2.0-litre CDTi diesel engine, the Vauxhall Insignia ecoFLEX is a little more inspiring on paper than the majority of these eco-special family cars. It looks good as well with its lowered ride height and sleek lines, giving buyers the option of doing their little bit for the planet without feeling like they've sold their soul to Bill Oddie.

We'd all like to drive a car that runs on grass clippings and puffs nothing but atomised Channel No5 from its exhaust but until the world's car manufacturers get their acts together on that one, the work of saving the planet will need to be done by more prosaic means. The growing glut of cars like Vauxhall's Insignia ecoFLEX might not be the last word in environmental-friendliness but they do offer real-world improvements and you can go out and buy one today. That's got to count for something.

There's no bigger issue facing the automotive industry today than the great big green issue. It wasn't that long ago, however, when many manufacturers were still content to pay lip service to it and hope it would go away. Legislation has changed all that and today, waiting for hydrogen fuel cell cars to arrive and save the planet at a stroke is not an option. Manufacturers have been forced into looking at short term ways of reducing emissions and saving fuel by a combination of new legal requirements and public demand. Cars like the Insignia ecoFLEX from Vauxhall are the result. Relying on simple engineering ingenuity rather than major technological advances, they might not be planetary saviours but they are a step in the right direction.

The Insignia ecoFLEX is based around the 2.0-litre CDTi ECOTEC diesel engine which generates 158bhp. That's a lot of power for one of these eco-special models which are usually focused far more intently on emissions and economy. The Insignia, with a 9.5s 0-60mph time, a 135mph top speed and 350Nm of torque from 1,750rpm, sets out to marry efficiency with lively performance. That torque figure can actually be increased to 380Nm via the engine's temporary overboost function, which means you get more pulling power than you would in a 3.2-litre V6 Audi TT.

"Going green doesn't have to mean reinventing the wheel or the internal combustion engine."

The Insignia's 2.0-litre diesel engine is an advanced piece of kit. It uses Vauxhall's Clean-Tech process to control emissions consistently through the different stages of its lifecycle. The combustion process in the cylinders is monitored up to one million times per minute so the engine management computer can adapt the volume and timing of the fuel injections to optimise efficiency. It's all clever stuff but it's common to all 2.0-litre CDTi Insignias, so what makes the ecoFLEX special?

Aerodynamics play the major role in the improved environmental performance of the Insignia ecoFLEX. The car is 10mm lower than a standard model which has the happy side effect of giving the car a more purposeful ground-hugging stance. There's also a number of modifications out of sight underneath the car which improve air-flow and lower drag while the radiator grille is partially closed off to send more air down the flanks of the car. The ecoFLEX also runs on Michelin's special low rolling resistance Primacy HP tyres.

The standard Insignia's sleek shape has a drag coefficient on 0.27 CD but the ecoFLEX model lowers that to 0.26. It sounds a trivial amount but the laws of physics reveal otherwise. When you double the speed of a car, the amount of engine power necessary to overcome the aerodynamic drag increases by a factor of eight. That means that even the tiniest improvements in aerodynamic performance can significantly reduce the amount of work the engine needs to do at a given speed, reducing fuel consumption. These aerodynamic enhancements have the additional benefit of reducing wind noise in the cabin and making the Insignia a more comfortable place to sit out long journeys.

The Insignia's styling has to be deemed a success in the context of the often mundane medium range sector but the designers were also intent on delivering practicality. The car is 21mm longer than the old Vectra at 4,820mm, and 50mm wider. The Vectra wasn't a cramped offering itself but the Insignia improves passenger space partly through these larger exterior dimensions and partly through a wheelbase that's extended by 35mm.

The cabin has set out to be as eye-catching as the exterior. The Vectra was always worthily dull but the Insignia has a number of features with the potential to set tongues wagging. The dashboard top wraps around at the sides of the interior in a steady curve that melts into the door linings. The effect is that the driver feels cocooned inside the car. The mood is helped by adaptive ambient lighting and a massive amount of attention has also been paid to the seats which have been specially designed to set new standards for ergonomics, comfort and safety.

The Insignia ecoFLEX goes up against a raft of eco-friendly rivals in the medium range sector and the battle for sales is likely to be anything but friendly. Vauxhall is obviously hoping that its offering will gain an edge by virtue of its hefty performance as most of the alternatives utilise relatively weedy powerplants to make their efficiency savings. Of course, the Insignia's additional pace will be reflected in the price.

Thanks to their streamlined design, sporty roofline and finely-tuned details, the regular Insignia variants feature an exemplary drag factor of 0.27. The Insignia ecoFLEX undercuts this figure still further. Its drag co-efficient of CD 0.26 makes it one of the most aerodynamic production saloons in the world and in this respect, the best Vauxhall saloon ever. As such, it requires less engine power to overcome air resistance than considerably smaller cars. This is key, because when doubling speed, the engine power necessary to overcome aerodynamic drag increases by a factor of eight. So if 13PS is necessary to overcome aerodynamic drag at 50mph, 107PS is needed at 100mph.

The ecoFLEX's reduced combined CO2 figure of as low as 129g/km means that business drivers will pay just 18 per cent Benefit in Kind tax - the second lowest band for a diesel car - down from 21 per cent for the already competitive 2.0 CDTi models. The lower CO2 also mean that all Insignia ecoFLEX owners will be better off by £25 per year due to its lower VED band. And with all drivers keeping a keen eye on the fuel gauge these days, the Insignia ecoFLEX rewards with an official combined figure of 57.6mpg - a 10 per cent improvement on the 2.0 CDTi model - which puts it among the best in class. It also means that the Insignia ecoFLEX has a potential range of over 850 miles.

Going green doesn't have to mean reinventing the wheel or the internal combustion engine for that matter. Vauxhall's Insignia ecoFLEX shows how much can be achieved with a slippery shape, an advanced diesel engine and some skinny tyres. Better yet, it achieves its efficiency gains without making the compromises that some of its rivals force on their owners.

Styling, performance and comfort don't suffer in the Insignia ecoFLEX and that can only help persuade buyers to take the greener option. That and the significant fuel economy and tax savings they stand to make.

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