The agency beat Lowe and DFGW in a three-way pitch for the £16 million Corsa task, which is Vauxhall's biggest brand. DLKW had originally battled against a longlist which also included Roose & Partners and Banks Hoggins O'Shea/FCB.
The pitch was run by Dean Barrett, the marketing director of Vauxhall Motors, and was handled through the AAR.
DLKW will work on a forthcoming campaign for the Corsa model. Sources close to the account have revealed the agency is already working on the task and is well into production on the next television spot for the marque.
The loss of Vauxhall's flagship Corsa brand will come as a blow to Lowe as it further weakens the agency's grip on the account, which it has held for 18 years.
In April, Vauxhall confirmed the successful agency in its above-the-line Corsa review would gain a place on the roster alongside the lead agency Lowe.
At the time Barrett commented: "We are looking for fresh ideas and creative treatments. He also confirmed that, after the appointment of the additional agency to the above-the-line roster, the two agencies would have to compete for each Vauxhall brand following the Corsa review.
Patrick Dunster, Vauxhall's marketing and communications manager, denied the decision to appoint DLKW had been taken, saying: "We haven't appointed anyone yet. The decision has yet to be made."
No-one at DLKW was available to comment on the win as Campaign went to press.
The Society of Motor Manufacturers and Traders puts Vauxhall UK's market share at 12.61 per cent, a figure that has dropped from its share last year of 13.6 per cent. The company is the UK's second biggest car manufacturer.
Vauxhall has developed a new brand direction in-house, and has been looking for an agency to develop its above-the-line communications.
News of DLKW's appointment comes as Lowe releases its latest work for Vauxhall. The agency's new Vectra television campaign features the Hollywood actor and star of Apollo 13 Ed Harris in a mock trial where he attempts to establish whether the new Vectra is, as claimed, an entirely new car.
The high-profile campaign sees Harris play a hotshot lawyer hired to prove these claims in an attempt by Vauxhall to overcome cynicism from consumers.