We sometimes think most things that are likely to be invented have been. Not so, as the engine in the latest Alfa Romeo MiTo has proved...
That's not to say there is nothing left but we do suspect that future inventiveness will be more incremental than groundbreaking. Hold that thought: now meet the Alfa Romeo MiTo in its latest form with the new MultiAir engine.
This, no kidding, is the most fundamental advance in the history of the petrol-fuelled piston engine since the arrival of fuel injection during the Second World War. It's an engine whose inlet valves are no longer opened by a camshaft. Well, not directly, anyway (we first told you about in March 2009.
Never in the history of human transport have little hydraulic pistons oscillated so fast and so continuously. That they can do this and survive in the heat of an engine is extraordinary. What, then, is the point?
I'm going to explain what MultiAir is and how it works. If you're not interested, skip a few paragraphs to see what I think of the fastest, grandest MiTo MultiAir, the new Quadrifoglio Verde for which an impressive 127 turbocharged kiloWatts are extracted from only 1.4 litres.
An engine works best when how much the inlet valves open, and the point in the four-stroke cycle at which they open and close, can be varied to suit the engine's need at particular speeds and levels of exertion.
Variable valve timing has been used in various forms for years to achieve this and has reached its greatest sophistication with systems such as BMW's Valvetronic which uses the valves themselves as the throttle instead of the usual air-flap connected to the accelerator pedal but it's still a mechanical system - and complex at that.
MultiAir is different. Four extra cams on the exhaust camshaft actuate four little hydraulic pistons, one per cylinder, and the oil in which they move in turn operates the inlet valves (two per cylinder) through pairs of further hydraulic pistons. Fine; the oil is acting like a hydraulic linkage, but why go to all this effort?
Well, because there's also an electric solenoid valve within that "linkage" that can bleed off controlled amounts of oil and thus alter both the timing and duration of the inlet valves' opening within the ultimate constraints of the actuating cam's shape.
This they do very accurately and over wider limits than previously achieved. So, the engine can run fast or slow, pull hard or gently, have great urge at low speed or rev vigorously like a sports-car engine, all by opening the solenoids accordingly.
QUITE AN ACHIEVEMENT
It's even possible, at low speed and under a light load, to open the inlet valves twice in one cycle and thus create a swirl of intake air to better mix the fuel thoroughly for a cleaner, more complete burn.
The system is all about using the fuel as efficiently as possible and for a petrol-fuelled, 127kW car to have CO2 emissions of only 139g/km along with 30 000km service intervals, is quite an achievement.
It begs comparison with another masterpiece of powerful downsizing, the VW Group's 1.4-litre engine that has both a supercharger and a turbocharger, but it's yet more frugal and ultimately simpler.
Automakers have been experimenting for years to create a viable, camshaftless valve-opening system for the flexibility it brings and Fiat Auto (the engine will also be launched in a revised Punto) has done it.
ADAPTIVE DAMPING
Does it work? Yes. The MiTo Quadrifoglio Verde is the best showcase: its engine is powerful, smooth, sonorous and satisfying. It seems to do all that is promised of it - enjoyment enhanced in this top model by a slick, six-speed gearbox plus adaptive damping that has sharpened the MiTo's usually rather rubbery responses, made the steering feel more natural and improved the ride over ridges.
Bigger wheels and clover-leaf badges in green faux carbon-fibre complete the picture.
With this engine, the MiTo becomes a fully formed car of great technical intrigue and considerable emotive pull but the cheaper 100kW version is also an interesting prospect at only 129g/km.
MultiAir is engine-downsizing at its most intelligent yet. - The Independent, London
The Rivals
Mini Cooper S:
Always a favourite, nowadays with 130kW turbo 1.6 engine and as much frisky entertainment as ever. Avoid too-firm Sport suspension and wheels option.
Renaultsport Clio 200:
Two litres and no turbo means a traditional route to an ample 150kW (200bhp, hence the name). Cheaper Cup version is a purer driving machine but its trim is basic.