Simplify the following text for a Grade 7 native English-speaking person.
Original: After the qualifying session for the British Grand Prix Mario Theissen announced that the team had decided to halt further development KERS ; of which BMW had been one of the strongest proponents , and focus instead on improving the car 's aerodynamics .
Simplified: After the the British Grand Prix , the team announced they would stop development KERS . They set their focus on improving the car 's aerodynamics ( how well the car moves through the air ) .