Turbos have been used on production cars since the 1960s. These compressors, driven by the vehicle's exhaust gasses, force more air into the cylinders. When combined with more fuel, that results in more power. Turbos can make a small engine perform like a much larger one.
Both GM and Ford introduced small turbocharged engines in the 2008-2009 timeframe that signaled the tech had matured enough to install in the company's least-expensive cars. Now automakers could use smaller, more efficient turbo engines and retain (or even exceed) the power levels of larger engines. Today, nearly every manufacturer has downsized its engines to smaller turbocharged ones with a boost in performance and fuel economy.
What changed? The design of the turbos themselves were refined. Parts were made smaller, lighter, and more responsive. Twin-scroll turbos and twin-turbo setups allow engines to make power and torque all across the rev range with very little of the lag that old-style turbo engines were known for. Modern turbos are constructed of stronger materials than the old ones. The popularization of direct fuel injection also contributed to turbo performance, because this form of fuel delivery helps cools the intake stream, which allows for higher compression ratios—and more reliable power.
Source : http://www.popularmechanics.com/cars/g2778/most-important-automotive-tech-milestones/