MPG: Motoring Propaganda Golddust

In the 'real world', with company car tax bands, high fuel prices, emissions tax, and dwindling resources, the only performance figures for a car that really matter are the claimed fuel economy and emissions. The critical word in that last sentence is 'claimed.' It's a long held trusim that the miles per gallon a manufacturer inserts into the small print at the bottom of a glossy car advert is optimistic at best. The neat loophole of heading it under the 'combined fuel cycle' umbrella allows car makers to justify their totals, by arguing they reflect a mixture of standard driving practices and situations, and in turn this variety produces such impressive numbers.

However the audacity of these claims has seemingly been taken to new heights (or lows) by the findings of a very recent examination of the Fiat 500 TwinAir, in the unsurpassable Autocar Magazine roadtest, which I thoroughly recommmend. Fiat claims that the cute little Cinquecento, powered by a revolutionary (no pun intended) 875cc 2 cylinder turbocharged engine, will achieve a faintly ludicrous 68.9 combined mpg. Now fundamentally frugal diesel cars have been able to get this kind of mileage for a couple of years, such as the VW Polo Bluemotion and BMW 318d. A naturally revvier petrol motor would struggle under normal circumstances, so Fiat have taken inspiration from the original vertical twin engine out of the 1957 Cinq and brought in 21st Century knowhow to create the TwinAir. And at first look, the benefits are quite tangible.

Two cylinders, ie half the number in a normal city car, equals less weight and internal friction. Less energy is lost through heat transfer, and the miniature turbo provides mid range boost to provide a par-for-class 84bhp. CO2 emmisions are a paltry 95g/km, the lowest of any internal combustion powered car on sale, meaning the lucky owner saves further money on tax.
So how then, did this lightweight, well designed, thoroughly tested city car manage just 35.7mpg on the combined cycle? Autocar's route covered the sort of driving you'd expect any modern city to be able to cope with when called upon, mostly urban miles together with occasional motorway and B-road work, and yet the Fiat coughed out only just over half the mileage it is allegedly capable of. How can this be allowed? If Apple released the new iPad ina  year or so's time and lauded it to have a fortnight's worth of battery life, only for consumers to discover it died after half an hour, trading standards and suchlike would have a field day. The credibility of Apple's designers and marketing dept. would be (further) decimated. Yet car makers continually appear to flout the rules by advertising their cars to be a damn site easier on petrol than they actually are, though customers are so used to this swindle that it fails to generate a meaningful fuss.
The fact is that somewhere, somehow, manufacturers have calculated on powerful virtual systems, taking into account all factors and actuators, what the maximum economy of their product is. Then they will put a trained test driver into an immaculately prepared example, on an empty, billiard-table smoooth test track, in perfect weather conditions, and achieve said mileage by monitoring all the car's systems and eeking out the very limits of its thirst. They are then perfectly within their rights to advertise these grand totals, despite the fact it would be irresponsible, leave alone unrealistic, to even attempt to drive in such a manner on the public highway. Traffic, impatience, human error, local geography, and carrying passengers mean it's practically impossible to get a Prius up past 72 mpg in proper usage. The cut and thrust of city driving puts so much stress on the tiny TwinAir powerplant that for all its green credentials, the fuel bill will still leave gullible owners in the red. And red-faced.

Don't expect this global fraud to be brought down anytime soon though, because the fact is, it brings about the most important aspect of the motor industry. It sells cars. It's even creating new ones. So by all means try a VW Bluemotion, a Mercedes BlueEfficiency, a BMW EfficientDynamics, or a Skoda GreenLine. Perhaps a Ford Econetic, a Vauxhalll ecoFLEX, a Volvo DRIVe, a SEAT Ecomotive. Maybe even a Ferrari HY-KERS. Just be ready to suffer two things. One is falling hook, line, and sinker for cynical marketing propaganda. The other is driving around in a car with a bloody stupid sounding badge on the back.