Taller gearing, smoother bodywork and low rolling-resistance tyres are all important parts of the ecoFLEX package that is allowing Vauxhall help fleets tackle spiralling fuel costs with improved operating economy.

But gadgetry designed to shut off engines when they’re not needed during traffic hold-ups is now the major player in the quest to make fuel go even further.

Introduced on eco versions of the Meriva, Corsa and Astra, GM’s stop-start technology has come of age after being made available on the Insignia, the smash-hit hatchback and estate range that has revitalised the company’s proposition in the D-sector.

After switching the engine off, it brings it back into action the moment it’s needed – and it seems to be making its mark with excellent economy in the two-litre CDTI 130 model on our long-term test fleet.

With 2,000 miles on the clock, it’s clear that the equipment is helping our car achieve averages on the better side of 50mpg, which represent excellent returns for a model offering spacious accommodation and the large carrying capacity that’s essential for the business user. As a further bonus, it also contributes to the lower exhaust emissions that pave the way for a welcome cut in tax liability.

While a strong economy performance establishes a sound business case, other credentials combine to make this version of the Insignia a particularly credible contender in a segment where competition has never been tougher.

Visually more upmarket than its predecessor, the Insignia is a comfortable car with an environment approaching the quiet, confident air that makes premium brands so popular with executives.

Thanks to having a higher sixth gear ratio than other Insignias, our eco model feels particularly well suited to long distance travel and its 70-litre tank is proving to be good for a realistic range of 700 miles.

Apart from an occasional reluctance to switch off after overnight parking, the car’s electronic handbrake works well, and provides an upmarket touch as the auto-hold function allows faultless starts on inclines.

The feature sits well in a specification list that includes climate control air conditioning, cruise control, a driver’s seat with powered height and lumbar adjustment and automatic lighting control.