stalking horse

The New York TimesにあったVolvo XC60のreviewから英語表現を拾います。stalking horseは「隠れ馬」のことで，これは「猟師が身を隠すための馬」のこと（『プログレッシブ英和中辞典』小学館）。さらに，そこから転じて「（選挙などの）当て馬候補」という意味があります（『プログレッシブ英和中辞典』同上）。ここでは「4気筒エンジンのシリーズを代表する他社の対抗馬」と解釈しました。（Koyamamoto）

A Preview of Volvo’s Heart-Healthy Future
Like a New York City mayor tilting at supersized sodas, several automakers have tried to forcibly wean Americans off their big, bad-for-you V8s. Six-cylinder engines are also being downsized in favor of 4s.
Now, for Volvo, even a 5-cylinder engine seems to be too much.
Among Sweden’s automakers, Saab is down for the count, leaving only Volvo to fight the industry’s global giants. Volvo itself has come under the wing of Geely, the Chinese automaker, since it was cut loose by Ford in 2010 in a $1.5 billion fire sale.
In the interest of efficiency — both in fuel consumption and in business operations — the latest XC60 crossover becomes a stylish stalking horse for Volvo’s new family of 4-cylinder engines. These modular engines, gasoline and diesel alike, share components and can be built in a single money-saving factory in Sweden.
http://www.nytimes.com/2014/06/01/automobiles/autoreviews/a-preview-of-volvos-heart-healthy-future.html?hpw&rref=automobiles&_r=0