Auto manufacturers are making their engines smaller by the day, reports emerging-technology Web site, Gizmag. Case in point: Mazda’s new turbocharged 1.5-liter “SkyActiv” four-cylinder diesel engine. The clean-burning diesel makes 105 horsepower at 4,000 rpm and an impressive 184 pound-feet of torque between 1,500 and 2,600 revs. Mazda says the all-important toque figure is equivalent to what would be found in a 2.5-liter gasoline engine. And because the engine meets strict emission targets, the company says no costly after-treatment system (usually a blue liquid that needs topping up from time to time) is required to curb emissions. To keep fuel consumption low, the new 2015 Mazda2 will feature Mazda’s i-Stop system, which shuts down the engine when sitting still “instead of wasting fuel idling.”

A new diesel option for the Mazda2 should produce impressive fuel-economy results.

Mazda joins engine-downsizing trend