Workers at Vauxhall's Ellesmere Port and Luton plants have hit a deal with their new owner, the Canadian car parts manufacturer Magna International, in a move that will secure the future of around 5,000 UK workers.
Under the deal the workers have agreed to a two-year pay freeze and 600 voluntary job redundancies.
The union said the deal secured the plants' future.
Vauxhall said in a statement, "We are pleased that the parties have secured an agreement that protects the jobs and prospects of the 5,000 Vauxhall staff in the UK."