1.5L I4 SMPI DOHC. Environmentally-Friendly Hybrid! All the right ingredients! This 2008 Prius is for Toyota fanatics who are aching for an exceptionally reliable car. The Prius scored the top rating in the IIHS frontal offset test. With a precision-tuned 1.5L I4 SMPI DOHC engine, it will wring every last mile it can out of a drop of fuel.