Every car maker is under pressure to make the cars that they make more fuel efficient. That means that a bunch of new technologies have made an appearance in showrooms. For example, some companies have gone the hybrid engine route. Some have gone the electric car route. Some have tried using technologies such as cylinder deactivation where some cylinders in an engine are turned off under light load to save gas. Some have started using continuously variable transmissions.
Mazda has gone a different route based on two premises:
- The internal combustion engine will still power more than 80 percent of vehicles by the year 2020.
- The internal combustion engine operates at only 30 percent efficiency. So even if you make minor gains of say 5 or 10 percent, that’s a major improvement.
Plus there’s another premise. Some of the technologies that car makers employ to save fuel take all of the fun out of driving. While fuel economy is important, so is the driving experience and Mazda would like you to get both. After all, they want to make sure that their customers get a healthy dose of “zoom zoom.”
Enter SkyActiv.
Mazda looked at the engine, transmission, body and chassis, and looked for ways to improve on them. Here’s what they came up with:
SkyActiv-G Gasoline Engine:
One of the things that makes the SkyActive-G engines unique is the high compression ratio that they have. A high compression ratio is desirable because it allows an engine to extract more mechanical energy from a given mass of air-fuel mixture due to its higher thermal efficiency. Your average gas engine has a compression of 10:1 and some high performance engine might get up to 12:1. The main reason why you don’t see many engines with compression ratios as high as 12:1 or higher is pre-ignition or knock. Pre-ignition or knock takes place when the air-fuel mixture ignites prematurely because the temperature and pressure are too high. That’s the sort of thing that can result in engines self destructing. Mazda has worked to make this a non-factor by implementing a 4-2-1 exhaust system, redesigned piston cavity, new multi-port injectors as well as other innovations to avoid pre-ignition or knock. That allows Mazda to bring a compression ratio of 13:1. However, they didn’t stop there. They then implemented Continuously variable sequential valve timing (dual S-VT) on the intake and exhaust minimizes pumping losses, reduced internal engine friction 30 percent, and dropped the overall weight of the engine by 10 percent. All of this adds up to a 15 percent savings in fuel versus a previous generation engine from Mazda of equal displacement. Oh, I should mention that you get this with 87 octane gas which keeps money in your pocket as high compression engines usually require higher octane gas which is more expensive.
SkyActiv-Drive and SkyActiv-MT six-speed automatic transmissions
A good engine needs to be matched to a equally good transmission. Mazda has two of them. In terms of the automatic, they’ve brought to the table all the advantages of of continuously variable (CVT), dual clutch and conventional automatic transmissions. Not only that, it has a full range direct drive (torque converter with a full range lock-up clutch) which delivers a direct manual gearbox-like feel. All of that plus a few other tricks give the automatic a 7 percent fuel savings. For those who like to shift their own gears, the manual is a smaller lighter package that’s optimized for front-engine, front-wheel-drive vehicles with easy and tight shifting. Plus its has reduced internal friction which is a very good thing if you want to save fuel.
SkyActiv-Body
It’s not just the engine and transmission that contributes to fuel economy. It’s the overall weight of the car. So if you can reduce the weight of the car while keeping it strong, that’s a win. Mazda looked at what they could do on that front and came up with a lot. They dropped the weight of the body by 8 percent but increased the rigidity by 30 percent. They could of stopped there as that is significant, but they did more. On top of making the body more rigid, they re-engineered the crash zones using multi-load paths so you’re safer. Plus they’ve improved the driving dynamics to give it more “zoom zoom.”
SkyActiv-Chassis
The final piece of the puzzle is the chassis. Mazda wants its drivers to have a “Jinba Ittai” feeling when people drive their cars. That’s a Japanese phrase that means “horse and rider becoming one.” Or in this case, car and driver becoming one. So they’ve re-engineered the chassis to deliver improved driving quality at all speeds by re-engineering the rear suspension mountings, trailing arm position, steering components and set-ups among other items. It’s also more rigid while being 14 percent lighter.
Net result?
The 2.0 litre engine used in the 2014 Mazda 3 that employs all of these technologies puts out 155 horsepower at 6,000 rpm and 150 pound feet of torque at 4,000 rpm. Need more power? There’s a 2.5 litre version that puts out 184 horsepower at 5,700 rpm and 185 pound feet of torque at 3,250 rpm. All while using around 7 litres per 100 KMs of gas in the city and around 5 litres per 100 KMs of gas on the highway in either case. Not too shabby if you ask me. Now I drove a Mazda6 GT briefly last year and came away impressed as it had the “zoom zoom” that Mazda drivers look for and from my rather unscientific observations suggested that it has great fuel economy. So clearly Mazda has got SkyActiv right.