Saatchis, which already handles the £4 million UK advertising for Lexus, will now be responsible for developing a campaign to accompany the pan-European roll-out of the model in May.
The RX300 is being positioned as one of the next generation of standard utility vehicles, which are described as a crossover between luxury cars and standard 4x4s. In this sector the RX300 will compete head-on with rivals such as the BMW X5 and Mercedes M-Class.
The review was called last month by Lexus' European director, Stuart McCullough, following his promotion from UK director in September 2002.
Saatchis and the Dentsu-owned BLD, which is Lexus' retained European agency, made final presentations in Brussels earlier this week.
David Brimson, the Lexus UK marketing director, said: "Saatchis had the best understanding of how the Lexus brand and its products will be interpreted in different markets. Our intention is to create common branding across Europe. Its idea avoided the risk of pan-European blandness."
Lexus claims to have created the SUV sector with the launch of the RX300 in the US in 1998. The model was launched in Europe in 2000.
Kevin Dundas, the managing director of Saatchi & Saatchi UK said: "We won this pitch because of the strength of our ideas that can be adapted across borders and medium."
The UK accounts for 50% of Lexus sales and is the second biggest in the world.