Vauxhall and Opel, the European operations of General Motors, have withdrawn applications for government help, citing long delays.
They said the 1.8 billion euros ($US1.2 billion) was still needed, but the process had been "much more complex and longer than anticipated".
The BBC reports Germany has rejected a request for state aid and the new government in Britain has put loan guarantees under review.
The companies said they would now have to fund their growth plans internally.
Earlier this month, Germany rejected a request for about 1 billion euros of loan guarantees.