When CAR drove examples of the new Fiat Punto at its local launch in Gauteng, first impressions were that the 1,3 JTD Multijet could be the pick of the range. Does the baby diesel have what it takes to beat its rivals in terms of performance and frugality?

When CAR drove examples of the new Fiat Punto at its local launch in Gauteng, first impressions were that the 1,3 JTD Multijet could be the pick of the range. Does the baby diesel have what it takes to beat its rivals in terms of performance and frugality?

CARtoday.com reported last week that the JTD’s 1,3-litre Multijet engine delivers 51kW at 4 000 r/min and 180 N.m at 1 750 r/min. Fiat Auto SA claim the Punto 1,3 JTD Multijet will reach a top speed of a claimed top speed of 164km/h, with a 0-100km/h time of 13,4 seconds. Fuel consumption figures are said to be among the best in the segment with a combined cycle of 4,5 litres/100km.

"This engine was amazingly quiet, even at idle, smooth and tractable from around 1 500 r/min. it also revved freely and consumption is bound to be equally impressive,” the correspondent wrote of the 1,3 JTD’s 1,3-litre 16-valve Multijet engine.

The powerplant is said to be one of the smallest and most advanced second generation Common Rail direct injection diesel engines of its kind and features multipoint injections, an intercooler and a particularly efficient combustion chamber shape.

Fiat Auto engineers added a plastic inlet manifold with directional ducts and reduced engine mass and dimensions - the result is a 1 248cc in-line four-cylinder power unit with a bore of just 69,6mm and long 82mm stroke. Four valves per cylinder are driven by twin overhead camshafts and, when clad with all its accessories, the engine weighs just 130kg.

“The Common Rail idea first came from the Zurich University research laboratories. Its premise is that if one continues to push diesel into a tank, the pressure inside will rise and the tank itself will become a hydraulic accumulator (or rail), a reserve of pressurised fuel ready for use. In 1990, the Unijet system developed by Magneti Marelli, Fiat Research Centre and Elasis and the Common Rail principle entered the pre-production stage.

In 1994, when this stage was complete, Fiat Auto completed development and put Common Rail direct injection diesel technology into production with the help of the Robert Bosch Company, pioneering the passenger car diesel trend that has become more and more the norm across the industry.

Despite the name, Unijet engines make two injections of diesel into the combustion chamber, a small initial injection and a bigger main injection. Multijet follows the same principle but can make up to five injections.

“Multijet Common Rail engines differ from the Unijet principle in two essential parts: the injectors and the electronic control unit, or ECU, a Fiat spokesman said. A smarter ECU was required to reduce the time between injections and the volume of the injection in order to fit more injections into the same amount of time in the combustion cycle.

But the ECU also needs to vary its strategy according to three parameters, namely engine revs, the amount of torque required at any given time and coolant temperature. While the Multijet engine is running, the ECU adjusts the injection arrangement in terms of number and the volume of diesel injected. When coolant temperature is lower than 60 degrees and torque requirements are low, two small and one large injections are performed very close together.

As torque increases, the number of injections drops to two: a small one and a large one. Under conditions of high engine revolutions and high torque demand, only one injection is performed. When the coolant temperature rises over 60 degrees, emissions are minimised by the injection arrangement becoming one small, one big and another smaller injection.

“The most noticeable advantages of the Multijet system is that “noise levels are reduced, refinement is improved in terms of providing better torque progression and enhanced flexibility”, Fiat said, claiming that the JTD “is as responsive as a petrol engine due to the diesel unit’s wide rev range. Because combustion is continually monitored and controlled, fuel efficiency also increases substantially while lowering particulate emissions”.

The merits of the Fiat Punto 1,3 JTD Multijet will be put to the test when CAR features a road test of the vehicle in the near future. The July edition of the magazine features a comparative test between diesel versions of the Citroën C3 and Hyundai Getz. To see how the output, torque and claimed performance figures of the new Punto 1,3 JTD measure up against the C3, Getz and other competitors on the South African market, CARtoday.com has compiled a table for comparative purposes. (Claimed figures denoted with an asterisk):

Model cyl/capacity max power max torque 0 - 100 km/h max speed fuel index
Fiat Punto 1,3 JTD Active
(R127 000)
4/1 248 cm3 51 kW 180 N.m 13,4 sec* 164 km/h* 4,5 litres/100 km*
Citroen C3 1,4 HDI
(R129 995)
4/1 398 cm3 50 kW 150 N.m 15,06 sec 169 km/h 5,5 litres/100 km
Hyundai Getz 1,5 CRDi
(R129 995)
3/1493 cm3 60 kW 191 N.m 14,84 sec 167 km/h 6,45 litres/100 km
Renault Clio 1,5 dCi
(R135 995)
4/1 461 cm3 48 kW 160 N.m 14,9 sec 163 km/h 5,85 litres/100 km
Opel Corsa Classic 1,7 DTI
(R137 400)
4/1686 cm3 55 kW 165 N.m 13,57 sec 175 km/h 6,84 litres/100 km
VW Polo 1,4 TDI
(R145 690)
3/1 422 cm3 55 kW 195 N.m 14,51 sec 175 km/h 6,26 litres/100 km

Original article from Car