Putt-putt-putt goes the car, a sound that Yusei still isn't completely used to. The comforting keening whirrrrrrrrr of a Momentum-based engine is something that's practically engraved in Yusei's being by dint of working with them so long, and the stuttering inconstancy of a steam engine's puffs feel jerky and off. He doesn't quite give it the same attention, but the fading sound as it drives away temporarily steals his focus until the word theory hits his ears.

"That...could be the case. If the benefits this 'magic' gives end up being a bigger priority than expanding other modes of energy..."

Like the neglect of transportation, for whatever reason.