"It's a technology waiting to explode in popularity, but it needs standards," McLaughlin said. "If Apple decides to do its own thing, what does that mean for us?"
Automakers see wireless charging as a way to eliminate the clutter of cables in the car. Audi plans to offer wireless charging in its next-generation A4 sedan and Q7 crossover, built into the center console with a signal booster for a better cell reception. It serves a dual purpose: allowing use of the phone without draining the battery while discouraging a driver from holding the phone in his or her hands.
The problem is, only a small share of phones have wireless charging out of the box. Other customers must pay $20 to $100 to get that functionality, either by buying a special case or attaching a sticky electronic receiver to the back of their phone.
Most of those receivers use Qi, put forward by a group called the Wireless Power Consortium. But it's possible that Apple could adopt its own standard, just as it uses its own Lightning charging cable.
"Apple, in my view, isn't eager to adopt standards when they think they can do something themselves and ensure a very good user experience," said John Perzow, vice president of market development for the consortium, in an interview.
When it launched the Lexus NX crossover late last year, Toyota intended to sell 100 percent of units with wireless chargers. However, consumers walked into the showroom and complained about paying for a feature they didn't want to use. Toyota changed its plans for the NX; now, 35 percent of units ship with Qi chargers.
Another early adopter was General Motors, which built a wireless charging tray into the center armrest of the Chevrolet Tahoe, GMC Yukon and Cadillac Escalade.
The consumer reaction has been mixed, said Elizabeth Hayes, an engineering manager for body electronics at GM. Most of her feedback tends to come from iPhone users who can't believe they need a special case.
"People are getting very tech-savvy," Hayes said. "The problem is they often expect their phones to do more than they actually do."