Jenson Button has also added ? 5m to his total in the last year .
Is now worth ? 58m , while Scot Dario Franchitti , a four - time IndyCar champion , is worth ? 50m .
Jenson Button has also added ? 5m to his total in the last year and is now worth ? 58m , while Scot Dario Franchitti , a four - time IndyCar champion , is worth ? 50m .