Vauxhall's new 1.6-litre 'Whisper Quiet' diesel shouts refinement but without a lot noise, says motoring editor Andy Russell.

Blue is the new green for the diesel market – or to be exact AdBlue – as manufacturers continue their relentless pursuit of lower and lower emissions.

Most people are aware of carbon dioxide (CO2) emissions but diesels also emit harmful nitrous oxide (NOx) and one of the latest to clean up its act is Vauxhall with its new BlueInjection 1.6CDTi turbo diesel engine which is available in Zafira Tourer, Meriva and now Astra.

AdBlue, a harmless, colourless additive, is the vital ingredient for reducing NOx so the engine complies with future Euro 6 emissions standards. Stored in a separate tank, which may need topping up between services, AdBlue is a mixture of water and 32.5% urea which works with the selective catalytic reduction system. It is injected into the exhaust where the ammonia reacts with NOx to turn it into nitrogen and water.

You may think it's all very worthy but is going to be dull to drive but far from it. With the 1.6-litre turbo diesel producing a healthy 136PS at 3,500rpm and 320 Newton metres of torque at 2,000rpm, it pushed the seven-seater Zafira Tourer along at a healthy rate of knots. It's also extremely flexible, pulling willingly from low engine speeds, but you need to stir it into life with the six-speed gearbox before it feels brisk.

Everyday driving saw 55mpg overall but a run soon pushed that to 60mpg and, with a light foot and long journeys, many owners will improve on that.

Vauxhall has dubbed this new-generation 1.6 CDTi the 'Whisper Diesel' and it certainly lives up to that for, in this case, it is the lack of engine noise and cold-start clatter that is very noticeable.

It's going to be an attractive choice for a seven-seater which is more about driveability and economy than outright performance, although this new diesel is no slouch.

It also adds to the appeal of the Zafira Tourer which is already one of the more attractive-looking people-carriers and more pleasant to drive.

For a relatively high multi-purpose vehicle it can be hustled along country roads thanks to a well-sorted chassis and well-mannered handling although body lean inevitably builds with enthusiastic driving but it remains confident through corners. So keener drivers won't feel hard done by while the passengers – all three rows of them – will appreciate the supple, composed ride quality.

The spacious interior is bright and airy, with three sliding middle seats, but the rearmost ones are best for children. Boot space is limited with all the seats in use but dropping two into the boot floor opens up a huge load bay.

Vauxhall's new turbo diesel is a significant addition to its ecoFLEX engine range but one thing this 'Whisper Quiet' engine will not be doing is making a lot of noise about how good it is.