The UK-wide agreement supplements Balfour Beatty's existing fleet of more than 8,000 vehicles when additional cars and vans are required.
Sixt Kenning key account manager Rebecca Sutherland said: 'Operating on a national basis, Balfour Beatty's transport needs can vary dramatically. Although it has a large existing fleet, the right vehicles may not be available at the right time and location for short-term needs.'
Balfour Beatty group fleet services commercial manager Mike Brown said: 'Transport is a vital part of our business, with our needs varying on a daily basis. Working to tight project deadlines across the UK we need a partner than can react to our needs on a national scale.'