Not so long ago, variable valve timing systems like Honda's VTEC and Mitsubishi's MIVEC were used to extract ludicrous horsepower from relatively small capacity engines.

Now, in an age of MPG rather than MPH, the carmakers are using these systems to meet a greener end, reducing fuel consumption and emissions.

Mitsubishi has announced a new version of its MIVEC variable valve timing and lift system is being used in a new, 1.8-liter 138-horsepower engine for the Outlander Sport compact SUV,  Lancer sedan and Lancer Sportback 5-door hatchback.

Combined with a new stop-start system designed for the cars' continuously variable transmission (CVT), Mitsubishi claims up to 12 percent improvement in efficiency when measured on the Japanese 10-15 mode cycle.

Japanese and European cycles differ from the EPA's testing methods but the changes should result in a 2-3 MPG improvement across the board, and every little helps.

The 4J10 MIVEC Engine

MIVEC used to be fitted in cars like the Mitsubishi Lancer Evolution and Japanese market only FTO sports coupe, giving an aggressive step up in power when the valve timing changed at high revs.

The latest MIVEC system uses variable valve timing, lift and duration to ensure that the air-fuel mixture is continually varied depending on engine demands. Strong torque can be delivered at low revs, power at the top end, and under lighter load fuel consumption can be reduced to a minimum.

The new system can also be used in single-overhead cam engines which reduces weight, size and cost.

Auto Stop & Go

Stop-start systems are a hot topic for manufacturers in the U.S. as their benefits are rarely reflected in better EPA mileage figures. Current EPA testing doesn't spend enough time at idle for stop-start to come into effect.

Even so, drivers who spend a lot of time in traffic shouldn't be misled, as an engine not running at all those stop lights or in heavy traffic is saving you a lot of fuel.

The new stop-start system works with Mitsubishi's CVT, previously only available on manual transmissions. It incorporates a brake-hold system to keep the car at a standstill on inclines until power hits the wheels, and a higher-capacity battery ensures your audio system and navigation still function when the engine cuts out and restarts.

MIVEC may no longer be used exclusively for performance, but the benefits for driving in the real world are bigger than ever.