ROLLS-ROYCE'S so-called 'baby Roller' has passed the design stage and is now undergoing engineering study. CEO Ian Robertson does not want to say how many units of the new car, due in 2009-10, will be made, but confirms that Rolls-Royce's entire production won't exceed 2,000 a year. The Phantom limo accounts for 800-plus units, while the just released Drophead Coupe will account for 200 or so.