CHARLOTTE -- Engineers were on hand Saturday as the Hydrogen Road Tour made a stop in Charlotte.

They answered questions and showed off the hydrogen power technology.

"The only difference between the car you drive [and] these cars is that there is zero tail pipe emissions," Roy Kim, with the Hydrogen Road Tour, said. "So there’s no tail pipe emission coming from the vehicle."

The cars are going from Maine to California with 31 stops along the way. But running on hydrogen can be a difficult task when it comes to refueling, because there are only 61 hydrogen stations across the United States.

"It's a domestically produced fuel, so we're not dealing with the world market demand like you see with crude oil prices," Kim said.

Barbara Smelser said she likes the idea under the hood.

"I think I would consider a hybrid," she said. "These cars are amazing. I had no idea we were at this point in the technology that they're actually on the road."

But they're not in a showroom just yet. Engineers couldn't say when the technology would be available to consumers.

But getting the cars to drivers "makes a lot of sense," according to Kim.

The tour ends in Los Angeles on Aug. 23.