Regional directors Simon Gow (north) and Terry Hunt (south) assume day-to-day responsibility. Harvey Menzies, previously an area business manager, becomes network business strategy manager.
The changes indicate fresh thinking at the company which will change its name from Rover Group to MG Rover Group over the next few months.
Chief executive Kevin Howe said the new name was intended to reflect total commitment to world-class MG and Rover products.
Production of the 1959 Mini is to end on October 4, with a cumulative total of 5,387,862. Meanwhile, BMW has given the first details about the replacement Mini which debuts at the Paris Motor Show on September 28.
New Mini will be built at BMW's Oxford plant which employs 2,500 people. Trial production is due to start early next year and the first cars go on sale next summer.
The model will be sold by BMW dealers “as a separate business unit”, with dedicated Mini staff and “usually” a separate showroom.
Exceptional road holding is expected to be a feature, as it was with the original model. Power will come from a 1.6-litre engine to be built in Brazil.
Prices are expected to start at less than £10,000 but the supercharged Mini Cooper - the derivative to be seen at the Paris and Birmingham shows - may cost up to £20,000.
Trevor Houghton-Berry, Mini UK general manager, said the Paris unveiling would be live on the brand's website - www.mini.com