Germans love the latest wave of touch-free car controls, which respond to the flick of a wrist or the swipe of a hand, as it means no messy fingerprints on their spotless dashboards. Italians, known for an extravagant hand gesture or two, are not so sure.

A simplistic stereotype, but it captures the split among the world's drivers over the newest in-car tech on display at the Consumer Electronics Show in Las Vegas this week.

Germany's BMW demonstrated a 7 Series car that recognises five simple gestures, from a finger twirl to the right to raise the music volume and a hand swipe to decline an incoming call.

Japan's Pioneer had a minty scent shoot out of a dashboard to revive a driver after a car seat sensor detected a falling heart rate, a possible prelude to nodding off.

"It's certainly weird, certainly odd and certainly unproven. But Pioneer is not off base to connect one sensory organ to others," said Mark Boyadjis, an analyst at consulting firm IHS Automotive.

Given that drivers have enough to do keeping their hands on the wheel and eyes on the road, touch-free controls for some non-essential functions makes sense. But it is not clear all drivers want gesture, eye-tracking or even lip-reading technology.

"The jury is out" on how widespread it will become, said Jeffrey Owens, chief technology officer for Delphi Automotive, which made BMW's gesture software.

National differences

The Japanese, some of the keenest consumers of novelty technology, are likely fans of Pioneer's 'bio-sensing system' that squirts out fragrance, said the company's marketing head Russ Johnston.

Enthusiastic visitors to Pioneer's booth at CES suggested cappuccino and peppermint as good wake-up smells, he said.

The Japanese were the first to embrace back-up, or reversing, assistance because they did not want to bang their cars, said Guillaume Devauchelle, head of innovation at French auto parts supplier Valeo, who identified cultural preferences as a huge factor in adoption.

"There's no universal solution," said Devauchelle, whose company hired an ethnologist to make sense of different cultures with different tastes. He pointed out Germans' dislike of touchscreens, the risks of gesture control with expressive Italians, and the eager uptake of any kind of new tech by the Chinese.

Regardless of national tastes, the market for gesture recognition technology in vehicles - and the cheaper, more prevalent proximity sensing, in which the approach of a hand will trigger a touchable menu screen - is growing rapidly.

IHS Automotive predicts a seven-fold jump in unit sales of such technology to 30.4mn in 2021 from 3.7mn today. But full consumer buy-in is an open question, and cost may keep such features a limited, luxury option.

Safety questions

Safety experts have cautiously welcomed dashboard simplification, but note gesture control and other such features may actually add to confusion.

"If a driver doesn't know how to use it, will that increase the distraction?" asked Henry Jasny, vice president of Advocates for Highway and Auto Safety in Washington. "There's no proof that it will improve safety."

Automakers are free by law to test an array of options in their cars. The industry has voluntary guidelines that say drivers should complete tasks in a series of single glances taking no more than 2 seconds each, for a total of 20 seconds.

Systems are never foolproof, noted IHS' Boyadjis, who said he once triggered a blaring radio with an innocuous gesture.

Car makers and industry watchers are divided on whether touch-free controls will catch on, or even be overtaken by self-driving cars.

The human-machine interface "will be the differentiator for car makers" after safety systems, said Rainer Holve, head of connected car automotive software for Elektrobit, a subsidiary of German auto supplier Continental AG.

But Boyadjis at IHS is wary of "differentiation for the sake of differentiation."

"BMW has the capacity to throw this arguably unnecessary but innovative product into the 7 Series, not too concerned with the cost... and wait to see if the seed grows," he said. "The rest of the industry is watching."