(Bloomberg) -- Toyota Motor Corp.’s top scientist warned that transitioning to electric vehicles too quickly could lead drivers to hold on to old gas guzzlers and called for hybrids to be given a longer leash ahead of a Group of Seven leaders summit in Japan.

Subsidies and restrictions targeting certain powertrains could make EVs attractive for customers who can afford it, but for others it might have the opposite effect, Gill Pratt, Toyota’s chief scientist and chief executive officer of the Toyota Research Institute, told reporters in Hiroshima on Thursday. 

It’s an oft-repeated argument by the world’s No. 1 carmaker: the transition to fully electric vehicles will take longer than people expect, and that a multipronged approach embracing hybrids and alternate fuels will be better for the environment and the auto industry. That’s drawn criticism and fueled concerns that Toyota is giving Elon Musk’s Tesla Inc., China’s BYD Co. and other battery-EV rivals an unsurmountable lead. 

“Eventually, resource limitations will end, but for many years we will not have enough battery material and renewable recharging resources for a BEV-only solution,” Pratt said. 

“Battery materials and renewable charging infrastructure will eventually be plentiful,” he said. “But it will take decades for battery material mines, renewable power generation facilities, transmission lines and seasonal energy storage facilities to scale up.”

Read more: Electric Vehicles Alone Can’t Solve Climate Change: Editorial

While Toyota and other Japanese carmakers pioneered hybrid technology, they have been slow to ramp up EV output. Several have promised to rapidly expand EV production in the next few years, but did so without elaborating on how and when they intend to phase out hybrid or gasoline-powered cars.

Battery electric vehicles “are an extremely important option,” Akio Toyoda, chair of both Toyota and the Japan Automobile Manufacturers Association, said during a briefing Thursday. 

Throughout his 14-year tenure as Toyota’s CEO, which ended in April, the grandson of the company’s founder was both lauded and criticized for his belief in an approach that involved selling BEVs alongside cars powered by hybrid or traditional internal combustion engines.

Critics say Toyoda’s strategy doesn’t square with the carmaker’s goal to halve emissions by 2035 and become carbon neutral by the middle of the century, an assertion that he has refuted. 

“The goal is to do something about global warming,” Toyoda said. “The mutual enemy is carbon dioxide.”

Koji Sato, the new Toyota CEO who took over in April, said that by 2026 Toyota will sell 1.5 million BEVs annually and roll out 10 new fully electric models. The world’s largest vehicle manufacturer sold 38,000 BEVs in the fiscal year that ended in March.

Read more: Toyota’s Shift to Electric Future Rests on Koji Sato’s Shoulders

That figure will reach 200,000 in the current fiscal year, Toyota Chief Financial Officer Yoichi Miyazaki said in May, and Toyota will build a BEV factory and invest ¥3.1 trillion ($22.5 billion) to make it happen.

In April, G7 environment and energy ministers pledged to reduce vehicle emissions by 2035 but stopped short of announcing any deadlines or interim goals after a meeting in Hokkaido, Japan.

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