First of all, the first BlueMotion petrol engine does not compare with the fuel consumption of the Diesel engine, although to be fair, one shouldn't compare it with a normal Diesel, but with a BlueMotion Diesel. Since the petrol version has an emission of 99 g/km, whereas the respective Diesel version achieves 89 g/km. If one converts the, for a Diesel unfavourable values, then it works out to a difference of just under one litre.
One must however, pay ones respects, since reducing a petrol driven car, without any compromises being made either as far as space or performance is concerned, to just under 100 g/km, is quite an achievement. It can even be had as an estate-car and a sports-van. It does however, cost a good €1000 more than an equally motorised car with a normal petrol engine. However, there is still a difference of €2.500 to the TDI-BlueMotion. It may well be an alternative for fuel-savers who don't clock up a very high annual amount of kilometres, even though petrol is quite a lot more expensive than Diesel is.
Despite being 15 millimetres lower, VW promises no loss of comfort. Believe this if you will, since even in the earlier models, which were only 10 millimetres lower, the stiffer suspension was noticeable. In addition, the allegation that a BlueMotion cannot be fitted with a tow-bar, is a a fairy-story. Indeed doing so does somewhat spoil the rear-end design, even if the tow-bar is removable.
Compared with the four-cylinder Diesel engine, this three-cylinder petrol engine, with its weight of 89 kg(!), is a good 50 kg lighter. Apparently the Diesel will also someday mutate to a three-cylinder. VW has managed to make this engine smooth running, without the help of any offset-shaft or shafts. This is achieved by applying a combination of various measures. To these belong specifically, the relieving of the crank mechanism, particularly the oscillating components. They are probably also becoming smarter and smarter, as far as how to shape the counterbalances on the crankshaft and what size they should be. In addition, the 2-dimensional flywheel also plays its part.
All in all, the internal friction profits through the lower mass in the crank mechanism. In addition, the bearing surfaces have been reduced in size. The TSI-BlueMotion still has a difficult stand when the torques are compared. Let's take the low 1500 RPM as a yardstick, the TSI manages only 175 Nm against the 250 Nm of the TDI. Indeed, this has always been the domain of the Diesel engines. Once the low RPM-range has been left, that's when the petrol engine compensates with wonderfully higher maximum revs, which in this case lie at 6000 RPM. Those who are not worried about the nearly €2.000 more for the direct shift gearbox, won't notice the missing 75 Nm either. If at any point they were even necessary, then the DSG would have already shifted down a gear. VW refers by the way, to the first GTI from 1976, which had five HP less. More interesting would be a top-speed comparison, and this was almost 25 km/h less, despite having a substantially smaller cross-sectional surface. VW themselves stated the consumption of the, at least 300 kg lighter GTI according to standard valid at that time, as being 8,0 litres/100 km, now that's real progress. 07/15