When I had a company 3 years ago I paid a PUC (personal usage charge) of �60.00 per month and it didn't greatly affect my tax code, this may have changed though.
Buy or rent a double cab pickup. The Nissan navarra is probably the best out there. 5 seats, 4 doors, reasonably economical, quick and comfortable to other pickups/vans etc. The liability is only �3,000 so you pay 22 or 40% of that in van tax instead of a percentage of the list price based on emissions.