Small on rear space, big on efficiency
German Nikolaus Otto had worked as a travelling salesman until the constant jokes about his profession got the better of him. That, along with his mechanical curiosity, prompted him to settle in Cologne, Germany, and tinker with piston engines.
In 1876, Otto succeeded in creating the compressed charge internal combustion engine that used four cycles: induction, compression, combustion and exhaust. It became known as the Otto-cycle engine, the basis of the modern automobile engine.
Not much has changed in the intervening 140 years, until Mazda — utterly bored with its Wankel rotary engine — decided to revisit Otto’s handiwork. Configuration Driven to meet escalating fuel-economy regulations, Mazda’s engineers knew there were more efficiencies to be eked out of the reciprocating-piston engine.
Boosting the compression ratio to a lofty 12:1 is one way, but it also generates excessive heat, which leads to premature ignition (or knock).
To squelch high temperatures, Mazda specified a lengthy exhaust header to prevent the hot exhaust from being drawn back into the intake stroke. Direct injection also mitigates heat (fuel cools the chamber), as do specially-shaped pistons and reduced friction measures. Dual variable valve timing, controlled electronically, permit rapid timing adjustments during cold starts.
Mazda called its blue-sky engine “SkyActiv” and launched it in the refreshed Mazda 3 sedan and hatchback for 2012. The 2.0-litre four cylinder made 155 horsepower and 148 lb-ft. of torque, working through a short-throw six-speed manual or six-speed automatic transmission with an aggressive lock-up clutch in its torque converter.
Sold alongside the regular 3, SkyActiv models were marked with blue rings around the headlight lenses. None of the 3’s verve was lost in the transformation; in fact, electro-hydraulic power steering and retuned shocks gave it a more nimble feel and offered more feedback in the curves.
“There’s that fun factor. It doesn’t necessarily feel like an economy car when driving,” posted one owner, adding, “SkyActiv is no gimmick.” It wasn’t hard to crack 5.6 L/100 km (50 mpg) on the highway with a light throttle.
Inside, the driver and front passenger enjoyed roomy but firm seats and faced a curvaceous dashboard ren- dered in fashionable carbon black. Rear seat space remained cramped for anyone six feet or taller, and the trunk was smaller than the class average. The split seatbacks folded down to extend cargo capacity.
Base 2012 models retained the 148 horsepower 2.0-litre four cylinder carried over from the previous generation 3, while the upgrade remained the 167 horsepower 2.5-litre four lifted from the Mazda 6. The MazdaSpeed 3 kept its turbocharged 263 horsepower 2.3-litre four-cylinder firebrand and six-speed manual transmission.
The 2013 models gained new electronic features, including a larger, optional navigation screen and USB audio input for most trim levels. The 3 was totally redesigned for 2014 and the 2.0-litre SkyActiv engine was revised to yield even more efficiency. Driving and owning the Skyactiv 3 Belying its save-the-planet mission, the 2012 SkyActiv-powered 3 could sprint from 0 to 97 km/h in 7.9 seconds with the slick manual gearbox, while the six-speed autobox was barely slower at 8.3 seconds.
Being slightly lighter and reinforced with better underbody bracing and additional spot welds, the SkyActiv 3 is no econobox wallflower. The front-drive platform is commendably rigid, the steering is precise and communicative, and the four-wheel antilock disc brakes retard velocity effectively.
On the downside, road noise is elevated to the point of being tiresome on long trips. Some disliked the car’s stiff suspension and hard, mileage-tuned tires.
Assembled in Japan, the 3’s reliabil- ity has been exceptional — except for the manual gearbox’s fragile clutch. The friction material wears like $30 sneakers, with some owners reportedly replacing the clutch in under 50,000 km (warranty coverage is limited to one year).
The automatic transmission may exhibit a faulty valve body that can affect driveability to the point that some cars go into “limp” mode or stop altogether. Headlights can flicker when the brakes are applied, caused by inadequate alternator output under certain conditions.
Other gripes, in small numbers, include weak air conditioners, cupped tires and some delinquent interior rattles.
Beyond these maladies, the SkyActiv-equipped Mazda 3 is a durable compact that impresses with its nimbleness and obsessive efficiency. Otto would have been proud. Tell us about your ownership experience with these models: Chevrolet Sonic and Land Rover Evoque. Email: toljagic@ca.inter.net.