In certain vehicles, the side curtain airbags for the driver and front passenger may have a faulty inflator. In the event of an accident, the affected airbags will not deploy, increasing the risk of passenger injury.

Honda will begin notifying owners on Feb. 10, and the affected airbags will be replaced for free. Owners can call Honda at 800-999-1009 or NHTSA’s vehicle safety hotline at 888-327-4236 for more info.

Called SkyActiv, the car's new 155-horsepower drivetrain — a direct-injection 2.0-liter four-cylinder with a six-speed manual or automatic — builds on aerodynamic tweaks to eke out competitive mileage: 28/40 mpg city/highway in the automatic Mazda3 sedan, 27/39 mpg with the stick. Aerodynamic shortfalls and a few extra pounds dock 1 mpg highway off the SkyActiv hatchback with either transmission.

How does the Mazda do in the real world? I took a stick-shift Mazda3 SkyActiv hatchback from our Chicago offices to the Detroit auto show to find out.

The results underwhelmed. With one passenger in tow going east, sharing parts of the highway drive. After the auto show, I drove solo back west. Between both legs and a few days of puttering around Detroit, we racked up 637 miles and averaged 50 mph. The Mazda's trip computer reported 32.9 mpg — a few mpg past the car's 31 mpg combined rating, but well short of its 38 mpg highway figure.

We've had trouble meeting the EPA's highway numbers in 40-mpg cars before, and the winter conditions took their toll. Temperatures on both highway legs were in the mileage-killing 20s and 30s. I headed east with light winds but returned west with a stiff crosswind: Southerly gusts in Detroit hit 37 mph on the day I left, National Weather Service data showed.

The SkyActiv 2.0-liter cranks out 13 more pounds-feet of passing-lane torque than its port-injected sibling, but it still needs a lot of revving for the Mazda3 to move out. Fortunately, SkyActiv's extra oomph manifests on the interstate, where you can add 5 or 10 mph in 6th gear at a reasonable pace. Some commuter cars still require chucking through gears to tack on highway speed. The SkyActiv 2.0-liter is no imposter for Mazda's gutsier 2.5-liter four-cylinder, but it gets the job done.

Will shoppers buy it? I think so. Lead-footers will still want the 2.5-liter Mazda3, but consider the SkyActiv 2.0-liter against the car's base 2.0-liter. At 12,000 annual miles, current national gas prices ($3.38 per gallon of regular, according to AAA) and the EPA's combined city/highway rating, SkyActiv saves $140 to $273 a year versus similar non-SkyActiv variants. That takes some sting out of the price difference between SV/Sport and (SkyActiv) Touring/Grand Touring trims: SV models start at $15,200, and Touring versions at $18,700 (excluding a $795 destination fee). The latter should be an easy find, as just over half the Mazda3 trim levels listed in Cars.com's new-car inventory are SkyActiv trims.

The Mazda3 accounted for 41% of Mazda's U.S. sales last year, outselling bit players in the commuter segment. But shoppers still bought more than two Honda Civics, Toyota Corollas or Chevrolet Cruzes for every Mazda3. Gas mileage has been a shortfall for the Mazda3, which is otherwise a nimble car. I suspect the revamped drivetrain will narrow the divide.