MOUNT LAGUNA, Calif. — Rolling down a narrow black strip on California’s S1 route — which threads across spines of the Vallecito Mountains, low sand desert far below to the east and fir-clad slopes on the west sliding off toward the Pacific Coast — a cool new compact machine from Mazda of Japan, the 2012 Mazda3, grips asphalt through knotted curves like a slot car locked in the groove of a serpentine track.

With independent suspension elements for springs and shocks floating wheels smoothly over road ripples as tires trace an aggressive line through all bends and kinks on this back road, our 2012 Mazda3 test vehicle expresses itself with nimble movements which mimic a mechanical athlete obviously capable of accomplishing the kind of road tricks you might expect from a sports car.

The fact that the 2012 Mazda3 bears an extended roofline encasing the boxy back end of a long-body 5-door hatchback and its form looks more like a carpooler’s sled than a racy sports machine casts an image in-congruent with this lively performance attitude, yet Mazda has never followed the conventional path in automotive design and the 2012 Mazda3 5-Door confirms the point.

Building an agile little hatchback has historical precedents in Mazda’s product line, tracing back as far as 1977 to a three-door subcompact hatchback called the GLC — Great Little Car. With only 65 hp from a 1.5-liter engine directed to the rear wheels, spunky GLC was thrifty but still fun to drive.

Commencing in 2004, Mazda used a global platform developed by Volvo to underpin new compact-class vehicles badged as Mazda3 4-Door sedan and Mazda3 5-Door hatch. These were redesigned in 2007, then again in 2010.

For 2012 Mazda3 models score a face-lift and cabin refinements, plus the optional new SkyActiv engine with fuel-saving and performance-oriented technologies.

The 2012 Mazda3 innovative SkyActiv plant — an aluminum 2.0-liter in-line-four with dual cams and variable valve timing (VVT) — features multi-hole injectors to enhance fuel spray characteristics and a high compression ratio of 12.0:1.

It delivers 155 hp at 6000 rpm with 148 lb-ft of torque at 4100 rpm with EPA fuel economy figures of 28 miles per gallon for city driving and up to 40 mpg on the highway.

New SkyActiv transmissions work with the SkyActiv engine — driver’s choice of a short-stick manual six-speed transmission or a smooth six-speed electronic automatic with manual shift mode.

The 2012 Mazda3 models consist of a large collection in two body styles with four engine variations and 11 trim designations.

The SkyActiv engine goes into 4-Door and 5-Door Mazda3i Touring and Grand Touring issues.

Mazda3i 4-Door SV and Sport models use a twin-cam 2.0-liter four-cylinder VVT plant netting 148 hp at 6500 rpm with 135 lb-ft of torque at 4500 rpm. Transmission choices are a 5-speed manual stick or 5-speed electronic automatic.

And 4-Door plus 5-Door 2012 Mazda3 Touring and Grand Touring trims pack a dual-cam 2.5-liter four-cylinder that achieves 167 hp at 6000 rpm and torque of 168 lb-ft at 4000 rpm. This larger engine links to either a 6-speed manual transmission or 5-speed electronic automatic.

But the 2012 Mazda3 also makes sweet car candy in 5-Door format:  The sport-tuned Mazdaspeed3 Touring special edition carries a DISI (direct injection spark ignition) 2.3-liter turbo-charged four-pack with exclusive six-speed manual shifter.

It musters 263 hp at 5500 rpm and up to 280 lb-ft of torque at only 3000 rpm.

Body styling of sedan and hatch differs, as the 4-Door features smooth contours on a bulbous form while the 5-Door shows edgy shapes to project an aggressive posture.

Styling revisions for 2012 Mazda3 models include a new fascia, redesigned grille and round foglamps.

Mazda3i SkyActiv models wear unique trim, such as an engine cover in deep blue metallic paint and headlamp clusters with transparent blue ring around the center lens.

Inside, there’s big-time cabin space magically crafted from the confines of a compact-class chassis with two buckets up front followed by a brief bench for three.

And the hatchback design with a folding rear seatback (split 40/60 in two sections) forges a cargo bay with 17 cubic feet of space when rear seatbacks are up.

Front seats carry firm bolsters on flanks and fit in sporty fashion when you toss the car around on a wiggly route like our course across the Vallecito Mountains.

The driver’s bucket makes adjustments for lumbar back support. Seat position is elevated so you sit erect in ideal position in relation to the leather-wrapped steering wheel and a shifter stick studding the center console.

The twin-meter instrument cluster shows new constantly-illuminated white graphic meters, while SkyActiv-equipped models have additional blue gradation backlighting.

Safety systems for the 2012 Mazda3 models include a big disc brake mounted at every wheel with electronic brake force distribution (EBD) and computer linkage to an anti-lock brake system (ABS), a traction control system (TCS) plus a dynamic stability control (DSC) anti-skid device.

The 2012 Mazda3 MSRP numbers start at $15,200 for a Mazda3 SV 4-Door with manual transmission and extend to $24,200 for the Mazda3s Grand Touring 5-Door.

Mazda3i SkyActiv 4-Door lists for $18,450 (manual transmission) or $19,300 (automatic transmission), with 5-Door SkyActiv models priced at $500 above 4-Door models.

2012 MAZDA3 COMPACT SEDAN AND HATCHBACK SPECIFICATIONS

• Description:
  • Compact 4-door sedan
  • Compact 5-door hatch
• Model options:
  • 4D Mazda3i SV
  • 4D Mazda3i Sport
  • 4D Mazda3i Touring
  • 4D Mazda3i Grand Touring
  • 4D Mazda3s Touring
  • 4D Mazda3s Grand Touring
  • 5D Mazda3i Touring
  • 5D Mazda3i Grand Touring
  • 5D Mazda3s Touring
  • 5D Mazda3s Grand Touring
  • 5D Mazdaspeed3 Touring
• Wheelbase:
  • 4D 103.9 inches
  • 5D 103.9 inches
• Overall length:
  • 4D 180.9 inches
  • 5D 177.4 inches
• Engine size:
  • DOHC 2.0-L I4/VVT
  • DOHC 2.0-L I4/VVT/SKYACTIV
  • DOHC 2.5-L I4/VVT
  • DOHC 2.3-L I4/DISI/TC
• Transmissions/speeds:
  • 2.0 Manual/5
  • 2.0 Auto/5/Sport AT
  • 2.0 SkyActiv Manual/6
  • 2.0 SkyActiv Auto/6/Sport AT
  • 2.5 Manual/6
  • 2.5 Auto/5/Sport AT
  • 2.3 Manual/6
• Rear/front drive: Front
• Steering: Electro-hydraulic power rack and pinion
• Braking: Power 4-disc, ABS/EBD/EBA/TCS/DSC/TPMS
• Air bags: 2 (front), 2 (side), 4 (curtain)
• EPA mileage est. city/hwy.:
  • 25/33 mpg: 2.0 M/5
  • 24/33 mpg: 2.0 A/5
  • 27/39 mpg: 2.0 M/6 SkyActiv
  • 28/40 mpg: 2.0 A/6 SkyActiv
  • 20/28 mpg: 2.5 M/6
  • 22/29 mpg: 2.5 A/5
  • 18/25 mpg: 2.3 M/6
• MSRP range, est.:
  • $15,200 to $23,700: 4D Mazda3
  • $18,950 to $24,200: 5D Mazda3
  • $24,000 to $26,135: Mazdaspeed3