This year's Frankfurt motor show was big, busy, and full of new concepts and production cars spanning the gamut from small electric cars to exotic supercars with prices in the millions.

Every German maker showed one or more electric or electrified concepts, and renewed talk of driving on electricity could be heard in every presentation.

But underneath the shiny new concepts and Teutonically confident pronouncements may lie fear and desperation.

DON'T MISS: BMW i Vision Dynamics Concept previews all-electric four-door sedan

That would be due to the continuing effects of the Volkswagen diesel scandal, which has brought far tougher real-world emission and fuel-economy testing.

That, in turn, has abruptly upended German makers' plans to lower carbon emission across their ranges using diesel engines.

"With their big vehicles, German carmakers are particularly reliant on diesel in their home market of Europe," summarized a Bloomberg article on Monday, just before the show opened.

2015 Volkswagen Golf TDI SE

2015 Volkswagen Golf TDI SE

BMW, Daimler, and VW Group, it said, "had been banking on the fuel-efficient engines to help meet ever tougher emissions rules that will tighten further early next decade."

With test results demonstrating that in real-world use, diesels sold over the last decade didn't meet the emission rules under which they were certified, European makers have agreed to modify engine-control software in millions of recent cars.

That in turn has cut demand for new and used diesel cars, because potential buyers fear cars that actually comply with the law may not have the performance or fuel economy for which diesels had been known.

Germany's huge and influential automakers have been caught short, in other words, and are having to tear up product plans through 2025 and figure out how they'll meet the inexorably lowering emission caps.

A particularly telling quote came from Thomas Goettle, head of the automotive practice at PA Consulting.

He suggests that under new test regimes, none of the three German carmakers can meet the existing and future EU limits on carbon dioxide emissions, which would subject them to fines.

BMW i Vision Dynamics concept, 2017 Frankfurt Motor Show [photo: Tom Moloughney]

BMW i Vision Dynamics concept, 2017 Frankfurt Motor Show [photo: Tom Moloughney]

"Carmakers need to pick one death," he told Bloomberg.

“They cannot risk the disgrace of missing climate goals," Goettle said, "while claiming technology leadership."

That means "they need to swallow" the substantially higher investment costs of electric cars to avoid exposure to huge fines for over-emitting.

CHECK OUT: Mercedes-Benz Concept EQA small electric hatchback debuts in Frankfurt

BMW was the first of the three to release a volume electric car, the highly sophisticated but unusual looking i3 small car. It is now planning both more all-electric cars and plug-in hybrids throughout its range.

As the subject of the diesel scandal, VW Group has made the most public about-face, embracing battery-electric cars and showing several different electric vehicle concepts while feverishly working on the shared MEB modular architecture that will underpin them.

It promised last year to have 30 different electric-car models on global markets by 2030, and this week it said it would offer electric versions of all 300 models in makes by 2030.

Volkswagen ID Crozz II concept, 2017 Frankfurt auto show

Volkswagen ID Crozz II concept, 2017 Frankfurt auto show

Daimler has lagged, but it too recently sped up its electric-car programs to bring more models to market sooner.

Can the Germans switch gears from diesel to plugs for light-duty passenger vehicles, while holding their profit margins, keeping powerful union employees happy, and maintaining their brand images?

It promises to be one of the most fascinating questions for the industry over the next five or 10 years.

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