Elias took the handle. He gave it a experimental push. It glided across the polished floor as if it were hovering on a cushion of air. "It’s nice," Elias admitted. "But can I collapse it with one hand while holding a crying infant and a bag of groceries?"

He paid the cashier, wheeled the box to the hatchback, and—after only two tries—slotted it perfectly into the trunk.

"This," Marcus announced, clicking a lever that sent the seat spinning 360 degrees, "is the Apex Voyager . It features puncture-proof tires, a five-point magnetic harness, and an aerospace-grade aluminum frame."