Investor sentiment is on a knife edge. Car sales are back in recovery mode in most major European markets, yet the fragility of the turnaround could yet be exposed by another economic slowdown while investors have flagged the potential danger posed by web-based services further down the road.

The rise of the likes of car hire app Zipcar and car-pooling rival BlaBlaCar are expected to present new challenges to mass-market carmakers such as Ford, GM, Volvo, Renault and Volkswagen while presenting fresh opportunities for existing rental networks.

Online taxi business Uber is another seeking a slice of the market with its UberPop operation, which links private drivers to passengers, though the U.S. company faces legal challenges in countries including France and Germany.

Cathie Wood, chief executive of ARK Investment Management, is among the growing band of investment professionals expecting a significant behavioral shift among the car-buying public.

"Thanks to web-enabled services like Zipcar, Uber and Lyft, household vehicles are beginning to feel like the stranded assets they are: high in cost but utilized on average only 4 percent of the time in a 24-hour day," she said.