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CAP Blog > CAP Blog > Martin's Blog
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Jul
8
Written by:
Martin Ward
Wednesday, July 08, 2009
Mazda i-STOP is their unique name and branding for a stop/start system. However, this system does not just have stop/start to help reduce Co2 emissions and improve fuel consumption; it also has many other systems on the car to aid i-STOP. The car we mainly drove in Germany was the four door Saloon but i-STOP is also available on the more popular five door Hatchback. The Saloon has never been a particularly good seller in the UK, as most people who buy a C sector car generally want the practicality of the Hatchback. However, the four door is a really good looking car with some great design lines and would be for me, a difficult decision on which one to buy. Would I prefer style or convenience?
 The Mazda3 with i-STOP is powered by a 2.0 litre DISI direct injection petrol engine that produces 151ps, goes from 0-62mph in 10.4 seconds and has a Co2 emissions output of 159g/km. The official combined fuel figure is 41.5mpg. For a 2.0 litre petrol car that is fairly light in weight, the 0-62mph figure does not look very exciting and you feel as though it should be much quicker. However, having driven it extensively around the region of Brandenburg, it did feel responsive and had more than enough power.
 The i-STOP operates the same as most stop/start systems. In a manual car when you come to a complete standstill and take your foot off the clutch, the engine will stop and as soon as you press the clutch again, the engine will fire up. How the engine fires up differs depending on the manufacturer as factors such as the amount of time taken for the whole process to work for example, are generally not the same. The Mazda i-Stop works on combustion in the piston chamber. We had a long presentation in Japanese, which was translated into English, on how it works. When the engine comes to a stop, the alternator positions the crankshaft using sensors to ensure the pistons are in the ultimate position, with the right amount of fuel and clean air mixture for a quick and smooth re-start. This can only be achieved by using a direct injection engine. The engine starts in 0.35 seconds, which Mazda claim is the quickest available on the market. However, the clutch does have to be pressed down half way before it re-starts. Some systems start with just a light touch or with very minimal pressure on the clutch.
Like all stop/start systems, the Mazda will not operate under certain conditions including being on a steep slope, if the battery level is weak, if the cabin temperature is too high or too low and also if the engine is cold or if the front wheels are turned at an angle. In Germany the outside temperature was +29deg C and we had the air conditioning set at 19deg C. The engine needed to keep running to ensure the temperature was maintained so the stop/start system wouldn’t work at traffic lights or road junctions. However, if you turned off the air con then it would shut down and start up in the normal way. Anyone who buys a car with stop/start has to realise that there are limitations as to when and where the system will work and to realise that the system is not just being temperamental.
 The new Mazda 3 is a very competent car; it is comfortable, has some nice lines and is a great alternative to other C sector cars. It will make the user-chooser lists whereas the previous car never will. The i-STOP is a clever system in all respects but as Mazda are offering a good choice of diesel engines with lower Co2, that are potentially more fuel efficient than the 2.0 litre petrol engine, the most natural choice would be to go for the diesel. However, the petrol engine is quiet, refined and the stop/start system does certainly work efficiently.
Prices for the Mazda 3 2.0 Sport i-STOP start from £18,025 for both the versatile Hatchback and the stylish Saloon.
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