BERLIN—Automotive group Volkswagen AG said on Friday that it would boost capital investment to €85.6 billion ($107.3 billion) over the next five years, raising concern that fixed costs are spinning out of control.

In its bid to overtake Japan’s Toyota Motor Co. as the world’s biggest car maker, Volkswagen has consistently been one of the industry’s top spenders. But investors are now concerned that rising capital spending could dent profits in the coming years.

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