The planned listing of Porsche AG has generated huge investor interest, Volkswagen and Porsche Chief Executive Oliver Blume said on Thursday, playing down concerns over how he will manage both companies following the IPO.

Attracting interest from a broad range of investors was important, Blume said, declining to comment on what proportion of Porsche shares Volkswagen plans to offer to retail investors as part of the planned flotation.

Volkswagen is offering shares to retail investors in Germany, Switzerland, Austria, Italy, Spain and France in a process run by Deutsche Bank.

In total, shares amounting to about 12.5% of Porsche's total capital will be listed. Investors estimate Porsche's total value could be up to 85 billion euros ($85.1 billion).

Only some investors have asked questions about Blume's dual role, he told Reuters on a video call, adding he viewed it as necessary for the executive of the Volkswagen group to also be in charge of a brand.

"If something about Porsche AG is being discussed on the board of the group, I'll leave the room," Blume, who became CEO of Volkswagen on Sept. 1, said.

"The strategic leadership of the Group and the operational management of a brand suit each other perfectly ... in my view the linking of the two is necessary."

Volkswagen announced on Monday it would list sports car brand Porsche AG this month or in early October. Some investors criticised the timing given that war in Ukraine and record high inflation are destabilising markets.

Some also questioned whether Blume, who has headed Porsche AG since 2015, would be capable of managing both companies.

"Funds that have ESG (environment, social and governance) scoring filters will not be able to consider the IPO. It's true that Porsche as a business is interesting but the governance is bad," Gilles Guibout, head of European equity strategies at AXA Investment Managers in Paris, said.

Still, the chief executive said in his first interview since the IPO was announced that he and Porsche AG's Chief Financial Officer Lutz Meschke were getting positive feedback in conversations with investors in Frankfurt, London and New York.

"Despite the market conditions, there is huge interest. That is a great success," Blume said, declining to forecast a valuation for Porsche.

The 54-year-old said he would spend Mondays at Porsche's Stuttgart headquarters, Tuesdays in Volkswagen's Wolfsburg office, and divide up the rest of the week.

Blume and other Volkswagen executives have long argued that listing Porsche would raise much-needed funds for Volkswagen's electrification plans while giving Porsche more freedom.

Asked what that would look like, Blume said the sports car maker's board would be able to make independent decisions and set its own financial goals without Volkswagen being able to override them.

Still, Blume would ensure the remaining brands in the Volkswagen Group - including Audi, SEAT, Bentley and others - would also be able to act freely.

"What's important is setting guidelines. The group acts like an investor and sets financial goals ... within the guidelines, brands can act on their own," Blume said.

"I will ensure there isn't excessive management of the brands," Blume said, echoing his predecessor as Volkswagen chief Herbert Diess who last year reorganised the group's leadership team to delegate brand operations and focus its efforts more on areas like software, charging networks and batteries.