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MIVEC™ (Mitsubishi Innovative Valve timing Electronic Control system)^[1] is the brand name of a variable valve timing engine technology developed by Mitsubishi Motors. MIVEC, as with other similar systems, varies the lift of the valves by using two different camshaft profiles. At low speeds, a mild (low-lift) cam lobe provides "normal" performance, while above a fixed engine speed a second set of cam lobes are activated, providing higher lift and duration; therefore a greater quantity of air into the combustion chamber which increases the power output.

MIVEC was first introduced in 1992 in their 4G92 powerplant, a 1,597 cc naturally aspirated DOHC 16 valve straight-4.^[2] The first cars to use this were the Mitsubishi Mirage hatchback and the Mitsubishi Lancer sedan. While the conventional 4G92 engine provided 145 PS at 7000 rpm,^[3] the MIVEC-equipped engine could achieve 175 PS at 7500 rpm.^[4] Similar improvements were seen when the technology was applied to the 1994 Mitsubishi FTO, whose top-spec GPX variant had a 6A12 1997 cc DOHC 24 valve V6 with peak power of 200 PS at 7500 rpm.^[5] The GR model, whose otherwise identical powerplant was not MIVEC-equipped, produced 170 PS at 7000 rpm by comparison.^[6]

Although initially design to enhance performance, the system has subsequently been developed to improve economy and emissions, and has been introduced across Mitsubishi's range of vehicles, from the i kei car to the high-performance Lancer Evolution sedan. Many implementations only vary the valve timing (the amount of time per engine revolution that the intake port is open) and not the lift.

In the early years of developing its MIVEC technology, Mitsubishi also introduced a variant dubbed MIVEC-MD (Modulated Displacement),^[7][8] a form of variable displacement. Under a light throttle load, the intake and exhaust valves in two of the cylinders would remain closed, and the reduced pumping losses gave a claimed 10–20 percent improvement in fuel economy. Modulated Displacement was dropped around 1996.^[7]