Bentley workers rejected a 4% annual pay increase. Only 90 votes cast during a ballot of 3,300 union members separated those in favour of the deal and those against it, reported the Staffordshire Sentinel this morning.
Steve Taylor, who represents members of Amicus, the Transport & General Workers' Union and GMB unions within the company, said: "We have been discussing the pay deal for 10 weeks, and this was effectively the last offer on the table.
"If there had been a bigger rejection vote then it would have shown the company what staff thought. As it is, it makes our position and that of the company to solve the issue more difficult."
Some Bentley workers are understood to have been dissatisfied with a below-inflation flat pay rise, and a bonus system with so-far undefined targets on attendance, quality and profits.
A spokesman for Bentley told the paper: "The deal was rejected, so the issue has been returned to the works council to see what can be done to resolve the matter."