A roster of top General Motors executives, including CEO Dan Akerson, North America head Mark Reuss, global design chief Ed Welburn and Cadillac marketing VP Dan Butler last night (Sunday, 8 January) launched the Cadillac brand's most serious attempt yet to challenge the BMW 3-series, Audi A4 and Mercedes-Benz C-class: the new-from-the-ground-up ATS sedan/saloon.