The 'Bluemotion' diet

I was talking to a fellow car nut earlier today about spin and rhetoric and how easy it is to see through it in manufacturers' press releases. Having given it some thought though, I think the joke's been firmly on all of us.

I have visions of the heads-of-industry chuckling to themselves behind boardroom doors for lapping up the "downsizing" spiel they've been glibly feeding to us for years. I'll use the VW range to illustrate my point although I'm sure if I devoted the same amount of time to it, this could have worked just as well with Ford, Renault, PSA, Nissan and other 'mainstreamers'.

Very popular bit of trivia this, but the Mk V Polo was bigger in every dimension than the Mk I Golf, the original family hatch. With the Mk VI even bigger, I suspected the Polo was now approaching Mk I Passat territory so I decided to look up the figures and sure enough, the current mid-range Polo is a 1.4 petrol that pumps out 85 horses in a car that weighs about 1100kg. Original Passat? The top of the range was a 1.5 petrol with 84bhp and it weighed about 1100kg.

So Polo Mk VI, as big as Passat Mk I with current Golf, current Passat and Phaeton bigger still. Whereas the Polo used to be the smallest car in the VW range, VW have had to come up with the Lupo to file in underneath and more recently the Fox. And if Frankfurt 2009 is anything to go by, there'll soon be an 'Aye-up' joining the ranks.

So while manufacturers want you to believe you're downsizing when you opt for a Polo over a Golf, you're only really opting for the size of car you should always have had and that's why "downsizing" is so painless nowadays. Because it fundamentally isn't.

Increases in specific outputs, thermal efficiency and specific consumption have been used until now to disguise weight gain and that's why engine manufacturers have been able to find the massive gains they have in economy and emissions performance over the past couple of years.

Prime illustration? The VW Polo Bluemotion! Just by gearing that trades in performance for economy, engine electronics that do the same, stiff, skinny tyres and minor aerodynamic revisions, you get closer to 90mpg when you really should be getting more like 60mpg. Future increases in efficiency are going to be much harder to come by because all it's taken so far is a change of focus while applying the same technology.

Legislation means gains afforded by technology like direct injection and DSG gearboxes are now being directed where they always should have been rather than just towards affording us more interior space, safety devices and other creature-comforts; more road footprint for same amount of cost-to-own.

Think about that next time you're agonising over the hardship opting for a 'smaller' car might make you endure.