(Adds background)

BEIJING, Nov 15 (Reuters) - Tesla has cut the delivery waiting time for all Model 3 and Model Y vehicles to a minimum of one week, it said on its website on Tuesday.

The U.S. automaker added to its electric vehicle inventory in Shanghai at its fastest pace ever in October, data from China Merchants Bank International (CMBI) showed, at a time when automakers and investors are bracing for a downturn in the world’s largest car market.

Tesla had cut prices for its Model 3 and Model Y cars in China last month to boost sales.

Last week, the company offered an additional rebate for buyers who take delivery this month and buy insurance from one of Tesla's partners. (Reporting by Zhang Yan, Twinnie Siu and Ella Cao, Editing by Louise Heavens and Louise Heavens)