Despite a rise in car sales for March, America's auto giants look set to intensify their incentives battle over the coming months.

Vehicle sales rose 3.8% last month compared with March 2003, but manufacturers are worried that ongoing violence in Iraq and the weak labour market might dampen confidence in the second quarter, traditionally the strongest period for new car sales.

As a result, General Motors has offered an extra $1,000 (€812; £541) cash-back on many models (on top of existing rebates of up to $3,500) and five-year interest-free finance deals.

Ford Motor Company and Chrysler Group both responded immediately by sweetening their offers.

Data sourced from: USA Today; additional content by WARC staff