Simplify the following text for a Grade 7 native English-speaking person.
Original: The engines were smaller and less powerful than those used in Formula One , and the cars were also smaller , lighter and cheaper than their big brothers , having two litre normally aspirated or 750 cc supercharged engines ( an option that was very rarely used ) .
Simplified: The engines 2.0 L normally aspirated or 750 cc supercharged . The 750 cc engines were rarely used .