Nascar Race Today

Taking the advice of his doctors, three-time Indy 500 winner Dario Franchitti announced his retirement on Thursday.

Franchitti - a four-time IndyCar champion who also enjoyed a brief NASCAR career - sustained head and neck injuries in a violent crash last month in Houston. Doctors warned Franchitti that continuing to race could be detrimental to his long-term health.

Considered one of IndyCar's all-time greats, the announcement sent shockwaves through the racing community. Here's what some of your favorite NASCAR drivers were saying.