The result of the ballot is expected to be announced on Thursday
Workers at Jaguar Land Rover have started voting on whether to take a pay freeze for a year and bring in a four-day week.
The car manufacturer offered the deal last month in return for no compulsory job losses for two years.
Workers' unions have recommended the 15,000 staff accept the deal, which is expected to save the firm £70m a year.
Based in Gaydon, Warwickshire, it also employs staff in Castle Bromwich, Coventry and Solihull and Merseyside.
Jaguar Land Rover, which is owned by Indian firm Tata, cut 450 jobs in January.
The result of the ballot is expected to be announced on Thursday.
The former Jaguar plant at Browns Lane in Coventry has been taken over by regional development agency Advantage West Midlands.
The agency said it was getting the site ready for new firms to move in.