A company has published an emissions database online...

Amid all the hoo-ha about Volkswagen's past and significant diesel emissions sinning, a very good result has emerged about the cleanliness of the company's new cars in real-life driving.

Emissions Analytics is a world-renowned company which measures fuel consumption and emissions with remarkable accuracy as a car drives down a real road.

It has just published a freely searchable database of NOx data for 112 cars recently tested. They're all current cars homologated to the EU standard. And it turns out VW Group cars show up well.

Diesel cars generally emit more NOx than petrols, and yet six VW Group diesels managed to get into the cleanest group. The only other diesel to do so was a BMW 320d.

The 244-car results for Euro 5 vehicles do have some VW diesels in the worst category, but others running the disgraced EA189 engine actually scored mid-table.

Emissions Analytics calls its results the EQUA air quality score. The company's founder and CEO, Nick Molden, tells TopGear that NOx is the worst offender in dirtying the air of London and other British cities, so it's OK to use just this one measure and call it an air quality score. He says that modern catalysts have largely solved the problems of carbon monoxide, unburned hydrocarbons and, from cars at least, particulates.

So the EQUA score is a letter, from A to H. Score A is equivalent to the NOx output in the laboratory EU test, so it's reassuring to know those cars actually hit the same result in the real world.

EQUA band E represents between three and six times the current lab-test limit. Of the 112 tested Euro 6 cars, 21 were in band E, including one petrol, a Focus 1.0 Ecoboost.

Band H is more than 12 times the cycle limit for NOx. Three cars in the Euro 6 batch scored H: the Fiat 500X with the 1.6 diesel, the Audi A8 V6 247bhp diesel quattro and the Ssangyong Korando diesel.

Still, there has been progress. Of the Euro 5 cars tested when they were new, as many as 53 scored an H.

The company intends to keep testing 200-300 cars a year to keep the database current. The test route, near London, is done to tightly repeated speed patterns in consistent weather and traffic by carefully practiced drivers. Molder says their style is intended to be very much like an average driver, not some special economy technician aiming at the best result.

The data is gathered by a gadget that looks like a small power station mounted on a bike rack on the car's boot lid. It is in effect a portable emissions lab. It's connected to the exhaust pipe, and via electronics to the cars brains and sensors. It samples the exhaust 100 times a minute.

The system also gathers data for other pollutants, and gives a fuel economy reading.