General Motors on Tuesday extended US market hefty cash rebates and interest-free loans on most of its vehicles until July 31, continuing its push for sales in a weak market, Reuters reported. The news agency noted that GM has been offering rebates of up to $US4,000 and interest-free loans for up to five years for much of the summer. Under the programme announced on Tuesday, GM reduced rebates on a few models but launched deals on 2004 vehicles with rebates of up to $1,500, the report added.