Tarcisio Joao Schneider, 48, crashed into a truck near the city of Passo Fundo, Scolari's hometown in the southern state of Rio Grande do Sul, the federal highway police said.
Schneider was alone in his car, a police spokesman told Reuters. The truck driver suffered no injuries.
A spokesman for Brazil's football confederation confirmed that Schneider is Scolari's nephew.
This was Scolari's second loss in the family in less than a month. In late May, as Brazil started training for the World Cup, he attended the funeral of a brother-in-law in Rio Grande do Sul.
Felipao, as Scolari is known in Brazil, started his second spell as the national team's coach in 2012.
After leading Brazil to their fifth World Cup win in 2002, he was widely seen as one of the few experienced names capable of handling Brazilians' huge expectations of a triumph on home soil.
- Sports & Recreation
- Rio Grande do Sul