“…To achieve the target, engine manufacturers take advantage of different techniques such as downsizing together with turbocharging (leading to an increase of specific power), 1,2 gasoline direct injection (GDI), 3 complex fuel injection strategies (to exploit charge stratification benefits), 4,5 variable valve timing, 6,7 innovative combustion and ignition processes, 8,9 and water injection. 10 Moreover, the possibility to hybridize vehicles cannot be ignored, which currently is a widespread solution as described in Franco Briguiet et al, 11 Seibel et al, 12 and Smirnov et al 13 However, most of these technologies are simultaneously ''pain and delight'' for designers. In fact, besides undoubted benefits, they introduce drawbacks which cannot be neglected.…”