2003 Toyota Prius Owners Manual - Page 161

112.Iridium-tipped spark plugs For detailed information on oil level check, see "Checking the engine oil level" on page 212 in Section 8-2. 113.Brake system REGENERATIVE BRAKE When the brake is applied, the electric motor used as a generator converts kinetic energy into electric energy. The regenerative brake works in the following operations. 1. When the accelerator pedal is released, the reduced speed equal to engine braking in a gasoline-fueled vehicle is obtained in accordance with the running mode position of the selector lever. Your engine is fitted with iridium-tipped spark plugs. 2. When the brake pedal is depressed with the selector lever in "D" or "B", the regenerative brake works. NOTICE Use only iridium-tipped spark plugs and do not adjust gaps for your engine performance and smooth drivability. 154