The MultiAir technology of the Alfa Romeo MiTo, put to the test

As we already anticipated a few weeks ago, the MultiAir technology is mainly a development of the FPT research group (Fiat PowerTrain). The MiTo will be the first model to incorporate it.

The invention is based on the premise of being able to manage the amount of air injected from each cylinder into the fuel mixture in order to control consumption and power, and to deliver the maximum torque both at low and high revs, with the maximum forming a straight line from roughly 1,750 to 4,000 rpm.

MultiAir technology

The new MultiAir engine has neither a camshaft nor a variable valve timing system. Instead, it features a cam that is not so long and pointed but rounder, to manage air intake more easily (see detail). This is achieved through an electronic control unit and a hydraulic system that, at all times, manages the opening and closing of the intake valves according to engine load, or in other words, how far down we press the accelerator.

That is why we can encounter countless situations and valve openings and closings depending on how the car is driven. Thus, when we require maximum power, we can speak of maximum engine load and output, with a full opening of the valves.

If, on the other hand, we require a strong acceleration at low revs, the system opens the valves fully but closes them completely before they fill, saving fuel in the process. Another option is when the engine is idling: since no full filling is needed, the opening is not complete but progressive, as is the closing.

Besides being cheaper, for the end user, in practical terms, fuel consumption is reduced by between 10% and 25%, and so are CO§h39Fiath40§ emissions. Even the 170 hp version drops below 150 g/km, so the registration tax stays at 4.75%. Power increases by up to 10% and, at low revs, torque rises by 15%.

In addition to the new engine technology, all models are updated with the Start&Stop system as standard. Although the test itself will be discussed at the end, the system works similarly to that of other brands. Whenever the gear lever is in neutral, the clutch is released and the car is travelling below 7 km/h, the system will operate, with a few exceptions such as a low battery charge, a cold engine, the engine having been off for more than 3 minutes, or high demand from the climate control, rear heated window or windscreen wipers, so as not to compromise the battery for the next start.

Finally, whenever the DNA selector is set to Normal or All-weather, the GSI system (Gear Shift Indicator) fitted to the Abarth 500 is active. It allows fuel consumption to be optimised according to accelerator pressure, indicating when to shift up or down a gear.

The engine in practice

After the theory came the practice, and we were able to experience first-hand what we had been told. Indeed, the theory held true and the feeling of the new engines was very positive. Although we only had a brief first contact, it was enough to get a sense of the new MultiAir technology.

Fuel consumption drops by around 15% on the motorway (in town it is very difficult to make a comparative measurement). Where the 120 hp version used to consume 6.9 litres per 100 km, we now obtained 5.7 l/100 km at a constant 117 km/h and an extraordinary 4.4 l/100 km at an average of 90 km/h. That said, these are very superficial figures, based on the on-board computer and a stretch of only a few kilometres.

The DNA system as always: it has no memory once the car is switched off and restarted, always returning to the Normal setting, which ends up being forgotten. We only notice it when we see the GSI acting or when the engine response is genuinely relaxed (around 2 seconds). In Dynamic mode the response is immediate, just as we were assured.

We have not been able to test the Start&Stop system much on other brands, although compared with the one in BMW it feels slightly abrupt next to this one, which is smooth. Another improvement of this technology is that starting has been improved: a full turn of the pistons is no longer needed for the check, a quarter turn is enough. This helps make the system smoother. If, when pulling away from a traffic light where the system has cut in, the car stalls, pressing the clutch restarts the engine without needing to use the key. This avoids the honking of impatient drivers at traffic lights.

As mentioned earlier, this system does not operate when the battery charge is low or its starting is doubtful (it is a few years old). This is monitored by a control unit on the negative terminal of the battery, whose function is to check its condition. To avoid damaging it, a false negative terminal has been provided, to which the jump leads must be connected in case of a fault or a flat battery (see detail).

Engines and prices

Although its release is planned later for diesel engines, for now this technology is only available on petrol engines. These are the new 1.4-litre engines with 105, 135 and 170 hp, the latter called Quadrifoglio Verde and available from January 2010. The less powerful ones have been available since 5 November at prices from 16,350 euros for the most basic version of the least powerful, up to 21,000 euros for the 170 hp. The intermediate one stands at 18,700 for the sole DISTINCTIVE version.

Performance varies, but across all three engines we can highlight emissions of no more than 139 g/km, an acceleration from 0 to 100 km/h in 7.6 seconds for the most powerful and 8.4 for the intermediate one (the 120 hp accelerates in 8.8 seconds), and top speeds of 218 km/h. Consumption is greatly reduced, reaching an average of 6 l/100 km for the most powerful, 5.6 l/100 km for the 135 hp and 5.8 for the least powerful.