Whitacre, in an address to employees Friday, also says he is recombining sales and marketing, placing them under Susan Docherty. She became head of sales when former CEO Fritz Henderson separated sales and marketing.
Reuss recently was named head of engineering, and before that ran the company's Holden operations in Australia.
Whitacre says Bob Lutz, who had been in charge of marketing, will remain a vice chairman and be an adviser on global product development. He also will help Whitacre learn about the business.