There is no doubt that with the need to reduce engine emissions that technology will see smaller capacity units and lighter vehicles. Fortunately modern technology doesn't always mean we will lose out on motoring enjoyment.
To prove the point about smaller and consequently lighter weight engines the new Fiat two-cylinder TwinAir petrol engine has a cubic capacity of just 875cc, but with a turbocharger added the power output is a healthy 85bhp. Even more significant is the fact that the turbocharger is specifically designed to boost torque, not just outright power.
TwinAir performance
This means that this vertical twin unit has a healthy 145Nm (74lb ft) of torque from just 1,900rpm. The engine has the lowest CO2 emissions of any production petrol engine in the world, just 92g/km and this also means a Combined Cycle fuel consumption of 70.6mpg for the semi auto transmission model or 95g/km and 68.9mpg for the five speed manual versions.
Now none of this means anything if the engine is so slow it makes the car a liability. But with the installation in the Fiat 500 Hatch or the 500C cabriolet top speed is 108mph and zero to 62mph takes just 11 seconds. This is better than many 1.0/1.2 and 1.4-litre four cylinder petrol engines.
But it means little for customers if technology comes at a price which is too expensive to buy or run reliably. Well road tax for the TwinAir is nil, for Londoners the Congestion Charge does not apply from January next year and the prices start at £10,665 for the 500 TwinAir Hatch and £13,665 for the TwinAir 500C.
500 TwinAir market
Fiat UK expects to sell around 4,000 TwinAir 500s, 85 per cent of them Hatch models. Trim levels are Pop, Sport, Lounge, byDiesel and Blackjack depending on which body style is chosen.
This means TwinAir models are £1,200 more than the conventional best selling 1.2-litre four cylinder petrol engine and £1,200 cheaper than the 1.3-litre MultiJet diesel. The TwinAir is cleaner in terms of CO2 emissions than both of them.
It is more powerful with better performance than the 1.2-litre petrol option and only a little short of the MultiJet diesel unit for fuel economy and performance. Buyers will need to do their sums if considering the TwinAir option but many customers will buy it because it is unique in character and different.
But of course twin cylinder petrol engines are not new in the car industry, remember the original Fiat 500, the Citroen 2CV from 1947 to 1982 and the Citroen LNA in the 1980's with opposed cylinder layout and the NSU Prinz 4 of the 1960's with a vertical twin?
And Jowett cars and Bradford vans and Utility estates from before the First World War until well after the Second World War also used twin cylinder petrol power. The common feature was dull performance but with a distinctive engine note.
Driving the Fiat 500 TwinAir
The engine note to some extent with the TwinAir is still there but this engine is far more 'rev-happy' with much more power and importantly it is the turbo-torque that really works. The revs happen very quickly and it is easy to hit the rev-limiter in first gear on acceleration from standstill.
The note of the engine sounds lazy so the natural inclination is to push the accelerator more and that really sends the revs spinning. Indeed the oddest characteristic about the TwinAir is how the sound bears no relation to the actual performance.
It might sound as though it is labouring but in fact boosted by the turbo the engine has everything in hand and in fact the gearchange indicator light is telling the driver to change to a higher gear even if driving feels a lower gear is required.
With two cylinders instead of more, engine braking was almost nonexistent. The standard fit Start&Stop system seemed to work equally well with this two cylinder unit as it does with a four-pot.
There is also an Eco button that selects a softer throttle setting and lightens the steering for in town driving and for semi auto transmission models it alters the gear shift patterns.
Fiat 500 TwinAir fuel economy
To be honest my driving colleague and I found the engine nicer to drive in the Eco setting even on country roads. To prove the point, in standard mode our manual gearbox Hatch recorded 46mpg and then 48mpg in the Eco mode.
Also interestingly, a same spec model driven solo by one of our colleagues in front of us at the same speed for the town and country test route returned 60mpg, so carrying more weight with two up did really reduce the fuel saving potential.
Downsizing is technology we will have to get used to and we have been seeing it for some while from normally aspirated 2.0-litre units going to 1.6 or even 1.4-litre direct injection engines with added turbochargers and superchargers. It really is going to be a small world.
Fiat 500 TwinAir MILESTONES
Fiat 500 TwinAir 3-door, manual, hatchback
Prices: £10,665 to £13,715
Engine/transmission: 875cc, two cylinder, in line, petrol with Start&Stop, SOHC, variable lift inlet valves, fixed timing exhaust valves, multipoint injection with turbocharger, 85bhp, 145Nm, (74lb ft) of torque from1,900rpm, transverse front mounted, 5-speed manual
Performance: 108mph, 0-62mph 11 seconds, 68.9mpg Combined Cycle 46-48mpg on test, CO2 95g/km, VED £0, BIK company car tax 10%
Insurance group: 5
For: Lowest CO2 emissions for any petrol engine, cheap to run, technically interesting engine in a desirable city car - a good combination for some
Against: High price over a conventional small four cylinder petrol unit, noisy at mid range speeds and above, little engine braking