What's the difference between the skyactiv g and X ?
The 'G' is essentially the same spark direct injection (DI) petrol engine as the gen-3 car's, which is a low weight, standard-ish engine design.
The 'X' engine is a far higher compression engine that uses spark DI for hard acceleration and on startup, then switches to the same type of combustion via compression (still DI) as diesel engines, thus giving a significant (20-25%) mpg boost when running in that mode (e.g. when the car is under low load - travelling in higher gears at [reasonable and] constant-ish speeds, e.g. on motorways, etc).
The 2L 'SA-G' engine gives only 122PS, whilst the 2L SA-X (which does also have a small supercharger) gives about 180PS and about 5% more torque. The better mpg figures are only when driven 'normally', not hard, when the SA-X engine goes back into a similar operating mode to the SA-G engine.
It's the first petrol engine to have 'mastered' this concept, and was introduced around 2019. Thus far, no reliability issues to do with it of note, but longer term, we'll have to wait and see. I think that the benefits are noticeable, but perhaps not quite as much as first touted.
The SA-G engine in the current gen-4 cars has been further de-rated (from the standard one* fitted to the gen-3 cars) for a 0-60 time of around 10.2 sec as opposed to 8.9 sec; the SA-X has a 0-60 time of around 8.2 sec.
* An uprated (different 'tune') 165PS version of the 2L SA-G engine was fitted to the top spec Sport models of the gen-3 car which had a 0-60 time of about the same as the current SA-X engine, but with a significantly lower (average) mpg. If you drove both 'spiritedly', I doubt if you'd notice much between those two cars in performance or mpg terms.
The SA-X engined cars mean you can drive normally most of the time and get that 25% boost in mpg and have at your disposal that extra 60PS if you need it occasionally like the gen-3 Sport Nav 165 did.
The issue really is whether it's worth the extra, especially as many alternatives, especially from the VAG stable, use smaller capacity (1 - 1.5L TSi) turbocharged engies that in real use appear to be just as fuel efficient as the SA-X engine but under moderate load, you don't have to give it quite the same amount of gas as the Mazdas, which means less noise/perhaps a more relaxed drive.
In the Mazda's favour (other than the styling) is that they are really good at handling and the 'traditional' torque converter autos are very smooth and more reliable (though there is a noticeable drop in performance/mpg of around 10%) than the VAG dual clutch system IF the car is used frequently in slow moving stop-start traffic, i.e. where you effectively 'ride the clutch' or need frequent gear changes.
Again, best to test drive each to see what you prefer - you may not need the extra oomph of the SA-X or you may not like other cars for other reasons. A lot of this is personal preference based on an individual's needs and likes/dislikes.
I test drove a standard (122PS) gen-3 SA-G car but found it not much of an improvement, performance wise (despite the figures showing it should've been significant) over my gen-1 1.6 petrol's if driven normally. It (and the gen-4 SA-G) would be fine as a direct replacement for my car, but I was looking for more on the performance side without needing to thrash it.
Unfortunately, the 2.5L SA-G engine won't be in any UK Mazda3s (it is in ones in North america and Down Under), which gives the same power and more torque than the 2L SA-X (obviously quite a bit less mpg), which is a shame, and likely the turbocharged version of that engine won't either (a top-spec gen-4 car is again only available in those other markets at the moment).
|