Krow has picked up Fiat's £3.5 million UK advertising account from Leo Burnett.
Although no UK-specific work has been created for the car manufacturer for some time, the start-up will now be placed on the roster of agencies eligible to pitch for pan-European Fiat business.
On the pan-European account, every roster agency pitches against each other for European briefs. This arrangement was masterminded by Fiat's international advertising co-ordinator, Gregory Pingree, last year.
Krow, which opened for business last September, will be entered into the competitive pitches for new assignments in place of Leo Burnett.
The decision cements Krow's relationship with Fiat, which began in February this year when it won the UK launch of Fiat's Alfa Romeo Brera coupe.
It beat Mother and United London in the final pitch.
The decision does not affect Leo Burnett's sister agency Arc, which will continue to handle the car manufacturer's direct marketing account in the UK.
The direct marketing business is now a major area of activity for Fiat UK, which cut its overall advertising spend from £25.5 million in 2004 to £7.4 million in 2005.
Other agencies on the Fiat roster include the Italian agencies Armando Testa and Saffirio Vigoriti, a number of Leo Burnett offices across Europe, agencies from the United network and Mother.
Fiat's most recent major pitch was held in September last year, when Armando Testa was awarded the business to launch the new-generation Fiat Punto model across Europe. The Italian agency beat Leo Burnett, United and Mother to the account.
Fiat's UK account was moved into Leo Burnett in 2002, following the agency's merger with D'Arcy after Publicis Groupe's acquisition of Bcom3.
Krow was launched in 2005 by Nick Hastings, Barry Cook, Malcolm White and John Quarry. Hastings is a former creative director of Euro RSCG and D'Arcy, while Quarry is a former chief executive of Arc for Europe, the Middle East and Africa. Cook is a former managing director of Leo Burnett and D'Arcy, while White is a former Euro RSCG planning director.
Krow and Leo Burnett were unavailable to comment.