The agencies pitched jointly, and will develop an integrated campaign to cover TV, print, outdoor, viral and a website. It will run across nine European markets, including Germany, Spain, France, Italy and the Benelux countries.
The Opel GT roadster is inspired by the classic Opel GT coupe that was produced between 1968 and 1973.
The model was unveiled at the Geneva Motorshow and will go on sale in March 2007.
Olivier Danan, the brand communications director at Opel, said the campaign would use "a clever mix of traditional and alternative media to max-imise buzz".
The website will go live in December and other activity will launch early in 2007.
180 Amsterdam has a place on the General Motors European advertising roster along with Delaney Lund Knox Warren & Partners and McCann Erickson Frankfurt.
Ivan Pollard, a partner at Naked, said: "The Opel GT roadster is a great car and part of a great company. This is a brilliant opportunity to demonstrate to GM a different way of doing things."
General Motors has no plan to market the Opel GT roadster in the UK.