Over the years, Fiat’s reputation in the UK has been something of a rollercoaster ride.
By its own admission, the dealers could do better and the products have not been the most reliable of their kind on the market. Things continue to improve on both fronts, but the one area where it’s hard to fault the Italian firm is its dedication to the development of the small diesel engine.
The next chapter in that story, which already includes pioneering common rail technology, is the launch of the MultiJet II powerplant. It will debut this month in the 500 and 500C, and also in the Punto Evo. The overall architecture and 1.3-litre capacity are the same as the outgoing MultiJet – a former International Engine of the Year winner – but new common rail injectors now better control the amount of diesel forced into the combustion chamber. The injectors on the original MultiJet engine are capable of up to five consecutive actions in the same combustion cycle. This was based on a hydraulic servo valve with an unbalanced shutter, which means it requires long strokes. With MultiJet II, the shutter is now hydraulically balanced, which allows for shorter strokes. The technology makes the injection sequence much faster and more flexible than before, allowing up to eight separate injections in the same cycle.
Fiat Powertrain Technologies (FPT) – which has developed the revised engine – calls this new mechanical set-up injection rate shaping. In conjunction with a new variable geometry turbocharger, the measurable outputs are, on the face of it, impressive. On the 500, power is up from 75 to 95bhp, and torque rises from 107 to 148lb ft. Performance also improves in every way. The 0-62mph time has dropped from 12.5 to 10.7 seconds, while the top speed is up from 103 to 112mph. Fuel consumption has also improved – the 500 diesel now returns 72.4mpg on the combined cycle, as opposed to 67.3mpg from the 75bhp MultiJet engine.
CO2 emissions drop from 110 to 104g/km. FPT engineers claim there’s an improvement in noise levels and flexibility of the car, too. “With those four main improvements it’s a win, win, win, win,” joked a Fiat UK spokesman. On the urban cycle, fuel consumption has been reduced by up to eight per cent thanks to Start&Stop engine shut-off technology, which now appears on the 500 diesel for the first time. The MultiJet II engine is obviously still homologated to Euro 5 standards, but it goes a long way towards meeting the forthcoming Euro 6 levels. FPT engineers also argue that by achieving such a marked improvement in combustion, they’re reducing the need of aftertreatment devices such as catalytic converters