Simplify the following text for a Grade 5 native English-speaking person.
Original: The initial 1996 IRL season , as well as the first two races of the 1996-97 season , featured engines with specifications left over from the rival CART series competition .
Simplified: For the 1996 season , the old CART specification engines were used . They were also used for the first two races of the 1996-97 season .