Mazda says it's because the original fuel consumption and emission figures were taken from pre-production vehicles, and production cars have since been tested, producing better figures.
It means that our long termer, which had previously been rated at 34.6mpg on the combined cycle, would reasonably be expected to be capable of 36.2mpg.
And for drivers who have taken delivery of post-November 13 registered models, their benefit-in-kind tax liability for 2002/2003 would be based on 19% of its P11d price instead of 21% – a result of the carbon dioxide emissions now being rated at 185g/km instead of 198g/km.
If means that two hypothetical drivers, one with a car registered on November 12 with the other with a November 13 registered model, would have a difference of £287 in their annual tax liability.
It certainly makes the Mazda6 more competitive with key rivals.
The 1.8-litre car is now in the same tax bracket as the 1.8- litre Mondeo, but an equivalent Zetec saloon has an on-the-road price £1,165 higher than our TS car.
As for the fuel consumption, our records show that this car has fallen short of the original 34.6mpg combined fuel consumption figure, although on the last two tanks of petrol, the lifetime fuel consumption figure has risen from 32mpg to 32.25mpg.
There has been a gradual improvement from 32.2mpg on the first of those tanks to 34.5mpg up to the last time it visited the filling station, and that also included a 90-minute traffic jam on the M25.
Perhaps the previous drivers have been too keen to take advantage of the short gearing and listen to the crisp exhaust note under acceleration. It can be rather intoxicating when the engine winds up to about 4,000rpm, but doesn't do your fleet's fuel budget any favours, nor your wallet if you pay for your own fuel.
This isn't to say that I've been driving like an octogenarian stubbornly stuck to 40mph on unrestricted roads. I've had some fun too, in small doses, but fuel consumption has improved.
However, this particular Mazda6's time at Fleet Towers is nearing its end. It's predicted residual value is stable – CAP predicts 30%, just one point lower than our original report in August. Later this month we will be enjoying the Mazda6 driving experience in a run-in 2.3 Sport model and look forward to reporting our findings.
Company car tax bill 2002 (22% taxpayer): £49.86 per month