Volkswagen was one of the first manufacturers to create a low-CO2 version of a supermini. The original Polo BlueMotion was introduced to the UK market in September 2007, and it shows how things have progressed in the last three years that its 99g/km CO2 rating, considered impressive at the time, is now equalled or beaten by several significantly larger cars, including the current Golf BlueMotion.
The new Polo BlueMotion beats that figure handsomely, and although its 91g/km doesn't make it any cheaper to tax (because its predecessor was already exempt from Vehicle Excise Duty, and this one would only be superior if the Exchequer paid you to drive it) its 80.7mpg combined fuel economy is also better and should therefore make it cheaper to run.
Part of the reason for the improvement is that there is more technology this time round. The current BlueMotion has quite an array of fuel-saving features, including a remapped ECU which makes the 1.2-litre TDI turbo diesel engine focus more on economy and also gives it a lower idling speed, plus brake energy regeneration (to help recharge the battery when the car is slowing down), higher ratios for the top three of the five available gears, sports suspension which lowers the ride height and reduces aerodynamic drag, more aerodynamic treatment in the form of new bumpers, side skirts and air intakes, a stop/start system which cuts out the engine when the car comes to rest, and the fitment of low-rolling resistance tyres.
The effects of this are seen most clearly if you compare the BlueMotion with the 1.6-litre diesel Polo reviewed here. Both cars have the same power output of 74bhp, and although the BlueMotion is not only more aerodynamically efficient but also lighter there's not a lot to choose between them in terms of performance. The 0-62mph time is 13.9 seconds in each case, and the BlueMotion's top speed of 107mph is only 1mph higher than that of the 1.6. But the "green" figures for the 1.6 are 65.7mpg and 112g/km, so assuming similar driving styles you'll use a lot more diesel in that one, to say the nothing of the fact that - horrors! - you'll have to pay some road tax.
Now, here's a thing. In 2008 a Volkswagen spokesman was asked to justify the high list price of the then-current BlueMotion, and he did so by saying that customers seemed to be happy paying more money for a car up front than they would save in annual VED payments during their ownership of it. If you agree with this you will not be concerned - though if you don't you will - that the second-generation BlueMotion costs, at the time of writing, £14,445 in three-door form and £15,045 as a five-door.
To spend more than this on a Polo you would have to pick, at the very least, a 1.4-litre petrol in SEL trim (the highest in the range) with £1240 worth of seven-speed DSG semi-automatic transmission. It would be more expensive to run, of course, but it would be a much nicer car, with far more in the way of standard equipment. The BlueMotion is based on the entry-level S trim, though admittedly the equipment level is slightly higher than normal since it includes cruise control, front foglights, a multifunction computer, semi-automatic air-conditioning, a better audio system, a bit of interior leather and more of that sort of thing. (Oh, and a tyre repair kit rather than a proper spare wheel, which is deeply unfortunate.)
The other problem with the BlueMotion is the noise it makes. The Volkswagen Group's three-cylinder diesel engines have always been loud, and although the current Polo is much better at noise suppression than the last one was (some members of the Golf team were brought in at the development stage for this very reason), it still can't do much about the enormous racket being made under the bonnet. If the relative lack of equipment didn't already make you feel that you were paying a lot of money for a cheap car, this certainly will.
And yet, like all other current Polos, it still has a big-car quality to it, and it's also fun to drive. It rides exceptionally well, the major controls operate smoothly, and you can fairly hurtle it along deserted country roads if the mood takes you. The only problem with all this is that you can enjoy the same effects much more cheaply by picking almost any other car in the range.
I like the BlueMotion, but only because it's a Polo and I like Polos. For me to want to buy one, it would have to be both cheaper and quieter than it is now.