Jaguar's Castle Bromwich factory in Birmingham will start building a new model - if workers agree to a new way of working.
They're being balloted tomorrow over changes to how they work.
The company wants staff to agree to work on Saturdays when required. Saturdays are staffed by volunteers, but the firm wants to be able to ask staff to work Saturdays as part of their normal working week.
The company says if staff agree to this then new models will be built at the plant which makes Jaguar saloon cars.
The Unite Union is telling members they should accept the agreement but in the past workers have rejected the idea.
Jaguar Land Rover, in a letter to the staff said if workers agree it will "result in significant investment, growth in employment and a more certain future."
The company has said it will bring a new model to the factory is staff agree. This could create 1,000 new jobs and secure the future of the factory until 2020 at least.
Two years ago there was a possibility that the Castle Bromwich factory was going to be closed.