Simplify the following text for a Grade 8 native English-speaking person.
Original: The most famous and most well-attended oval race in the world is the annual Indianapolis 500 ( Indy 500 ) in Speedway , Indiana , sanctioned by the IRL ; in the United States , it is common to refer to open-wheel cars as Indy Cars because of their recognizable appearance at the Indy 500 .
Simplified: The most famous the annual Indianapolis 500 ( Indy 500 )