Like it or not, the majority of the world's vehicles are still powered by internal combustion engines, rather than batteries, hydrogen and other alternatives.

The good news is that carmakers are still finding ways to improve the good old reciprocating piston engine.

Even in the last few years, internal combustion has taken huge steps forward to reduce emissions and fuel consumption--while also satisfying consumer tastes for more performance.

Below are five engines which have been, or will be, a significant step forward for the common engine.

Fiat MultiAir

Fiat's MultiAir technology can be found in the Fiat 500 and Dodge Dart. The patented technology uses electro-hydraulic intake valves to constantly vary the amount of air entering the combustion chamber.

It allows the engine to optimize the fuel and air mixture almost infinitely, depending on load, engine speed and other factors. It eliminates the need for a traditional throttle valve too, improving intake air flow. Fiat claims 10 to 15 percent more power and torque, with 10 percent lower consumption and up to 60 percent less oxides of nitrogen.

In the 2013 Dodge Dart Aero, that's enough for 41 mpg on the highway, yet it produces 160 horsepower and 184 lb-ft of torque at only 2,500rpm.

Ford Ecoboost 1.0

Soon to arrive in the U.S. under the hood of the Fiesta subcompact, Ford's 1.0-liter, turbocharged three-cylinder is making a big stir in Europe.

It's the perfect example of a downsized engine. Rather than using a regular, 1.6-liter, four-cylinder gasoline engine, the 1.0 EcoBoost uses a smaller capacity, with direct injection and turbocharging. This reduces emissions and fuel consumption to tiny-engine levels, while maintaining the performance of a bigger unit.

Ford even installed a tuned unit in a Formula Ford single-seat race car, capable of 60 mph in 3 seconds, and 47 mpg at a 75 mph cruise.

Volkswagen TDI

It's rare to find a Volkswagen group product in Europe which isn't a diesel, and they're becoming increasingly common in the U.S. too.

It isn't hard to see why--the VW 2.0-liter TDI (and its smaller and larger counterparts available in some markets) is smooth, refined, punchy and economical. Yet it doesn't require customers to change their habits. You can fill up as normal, drive as normal, yet see an extra 10-15 mpg over a regular gasoline car.

VW has long been an advocate of diesel technology, and continual improvement has made their TDI models quicker and cleaner than ever.

BMW 3-Cylinder 1.5

BMW's downsized three-cylinder engine hasn't been launched in any production model yet, but it's set to be a significant engine in the company's future plans.

Firstly, it'll come to the U.S. in the nose of the next-generation MINI. Second, it will likely power such models as the 1-Series and 3-Series, plus derivatives of each, in several markets worldwide. And lastly, it's the powerplant joining an electric motor in BMW's exciting i8 plug-in hybrid sports car.

BMW is concentrating on downsized gasoline engines for good reason: Impending 'Euro 6' emissions regulations in Europe will really put a squeeze on diesel engine emissions, making them significantly more expensive to produce. That raises the cost of the cars themselves, and sales may decline--and economical gasoline engines will see the biggest benefits.

GM LT1 V-8

Yeah, we know.

But in a free country, there will always be customers who want a big, gas-guzzling V-8 under the hood--and kudos to GM for improving their small block engine with the latest LT1 version.

In the soon-to-be-unveiled Corvette, it has 30 mpg potential--a significant improvement on the current car, which gets 26 mpg highway. And as we all know, the biggest gains come from the least efficient cars.

Trick technology includes improved variable valve timing, direct injection, and cylinder deactivation. It's also 800cc smaller than the old LS-series, yet produces more power. That, we think, sounds like a win for everybody.

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