Continental, a major supplier for automakers around the world, has come out with a bold prediction: internal-combustion engine development by German automakers will essentially end by the year 2025.

The supplier, which makes exhaust-gas-cleaning systems for diesel cars and nitrogen oxide-measuring sensors, lists several factors contributing to its prediction: the increasing costs of development, the end of diesel's dominance, and an overall shift to electric cars and other alternative propulsion methods.

Specifically, Continental CFO Wolfgang Schaefer predicts 2023 will be the final hurrah for German engines running on fossil fuels.

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He believes one final generation of internal-combustion engines will be developed and launched by that date. Then investment and engineering will taper off after 2023, with 2025 sealing the engine's fate with the very last refinements.

"A new generation of combustion engines will again be developed, but after that (around 2023), a further development will no longer be economically justifiable because more and more work will switch into electric mobility," he said in an interview with Reuters.

Schaefer's prediction comes at a time when the use of fossil fuels for transportation faces greater scrutiny than ever across Europe.

Audi e-tron Sportback concept, 2017 Shanghai auto show

Audi e-tron Sportback concept, 2017 Shanghai auto show

France, the United Kingdom, the Netherlands, and Norway have all announced similar plans to phase out sales of cars powered by internal-combustion engines.

The Netherlands and Norway want the ban to be in place by 2025, while France and the UK have targeted 2040 for implementation.

READ THIS: UK to ban diesel, gasoline car sales by 2040; follows France, Norway, Holland bans

All the while, European authorities continue to investigate Volkswagen Group over diesel emission cheating and have alleged BMW, Daimler, and VW Group colluded to manipulate emission regulations.

Each German automaker now plans to update software on its diesel-powered vehicles to curb emissions further, at no cost to customers.

Audi e-tron Sportback concept, 2017 Shanghai auto show

Audi e-tron Sportback concept, 2017 Shanghai auto show

Although German automakers are far from confirming any such plans to end internal-combustion engine development, it may be inevitable.

Volvo previously announced it will move to launch only electrified model lines from 2019 (meaning hybrid or electric), while every German maker now plans at least a few mass-produced electric vehicles that it would have sneered at just eight years ago.

CHECK OUT: Volvo to electrify all cars from 2019: 'end of internal-combustion engine alone'

All of this comes as likely timelines for peak oil demand are debated. Some analysts believe oil consumption could reach its maximum as early as next decade.

Aggressive government policy and future battery technology will ultimately guide the internal-combustion engine's future, but the days of new and better engines are—for the first time ever—starting to to be viewed as numbered.

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