"One of the biggest trends right now in automotive engineering is improving engine efficiency and fuel economy," says Giorgio Rizzoni, director of Ohio State University’s Center for Automotive Research (OSU CAR). "This includes downsizing, down-speeding, direct fuel injection, and boosting."
Other engineering trends focus on improving transmissions (adding speeds), accessory load reduction through the intelligent energy management of other vehicle components, vehicle electrification, hybridization, improved battery management systems, new battery chemistries, and power electronics.
The two main benefits in downsizing an internal combustion engine are thermodynamic and mechanical. "From a thermodynamic point of view, the engine operation will move towards higher loads, at which the engine efficiency is higher," says Rizzoni. "From the mechanical point of view, the positive aspect lies in the reduction of the friction in the piston units, together with the reduction of the number of cylinders."
Downsized engines are lighter than conventional engines, thereby reducing vehicle mass and the improving vehicle fuel consumption. Turbocharging recovers the energy of the exhaust gasses to increase the inducted charge, therefore increasing the power-to-displacement ratio. "A downsized and turbocharged engine has the potential to have the same or better performance as a non-downsized, normally aspirated engine, with the advantage of a significant increase of fuel efficiency," says Rizzoni.