The decision marks the first time the car manufacturer has hired a UK-based agency since its parent, General Motors, introduced Cadillac to the UK in 2003.
Lateral will handle marketing of the Cadillac BLS, a small saloon car due to launch in the second quarter of 2006. The launch will form a key part of Cadillac's European push and is aimed at the market led by the BMW 3 Series.
Above-the-line advertising supporting the UK launch is expected to be adapted from work by Cadillac's European agency, the Frankfurt-based Buehler & Partners.
Neither Lateral nor Cadillac would comment.
Separately, the luxury car manufacturer Bentley has appointed a digital agency, Global Beach, to handle its worldwide interactive marketing for the next three years. The appointment covers website design for all marques and online advertising.