The Vauxhall Insignia's big-selling 2.0-litre diesel engine has come a long way since 2008. In the current version it would bear comparison with plenty of premium-brand diesels on overall quietness.

Its manners aren’t perfect: you can still feel little shimmies on occasion through the pedals, and you’ll know when the crank’s spinning beyond 3000rpm because it’s fairly vocal – albeit low on coarseness. All in all though, the car has entirely decent mechanical refinement – certainly quiet enough for fairly relaxed, high-mileage motorway use, which is what most owners will care most about.

The turbo petrol engines offer performance with efficiency and are worth considering

Performance level in the 138bhp Ecoflex model is as modest as the cabin styling, particularly in 5th and 6th gears which are the ones lengthened for the sake of economy. But that’s not to say it’s bad. The Insignia’s a big car, but the engine’s fairly generous swell of mid-range torque makes it flexible and risk enough when accelerating through 3rd and 4th. Shift quality is good.

The starter-generator faltered under stop-start conditions once or twice during our test, failing to restart the engine at the first time of asking – but, while irritating, that’s a far-from-uncommon problem with economy diesels these days. And you can always turn it off; something that won’t prevent you from returning a real-world 55mpg on a mixed run.

While the diesel is particularly competitive with rival manufacturers' offerings, the 1.4-litre turbocharged petrol engine is worth considering for the way it adopts a forward-looking approach of downsizing. It has replaced the wheezy old 1.8-litre unit throughout most of the Insignia range, and pulls cleanly and with purpose from low revs, thanks to 147lb ft of torque from 1850-4900rpm.

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Overtaking no longer demands a long straight and plenty of patience. It’s a refined unit, too, and there’s nothing strained about the engine note even at high revs.

Higher in the petrol range you'll find a detuned version of the Astra VXR's 2.0-litre turbocharged engine, which is likely to play a very small part indeed in the overall sales mix. Above it sits the 321bhp VXR Supersport model.

The hottest of all the Insignias was developed to give premium German marques a bloody nose, and against the odds it does. Sort of. Think of the Insignia VXR as a cheaper and rarer Audi S4, but one that'll romp on to an ungoverned 168mph top speed if you allow it to. It has a curious kind of power delivery, and like the rest of the Insignia range, isn't the most involving machine to drive. But it offers lots of bang-for-your-buck.