 Complete the following phrase:  After foreign cars became the norm, foreign drivers began competing in the Indianapolis 500 regularly, choosing the United States as their primary base for their motor racing activities. Brazilian Emerson Fittipaldi, Italian Teo Fabi, and Colombian Roberto Guerrero were able to obtain good outings in the 1980s, as was Dutchman Arie Luyendyk. However, it was not until 1993 that reigning Formula One World Champion Nigel Mansell shocked the racing world by moving to the United States, winning the CART PPG IndyCar World Series Championship and losing 