Providing power to a couple of electric motors is an absolute unit of a battery pack at 384 kWh in size. Hyundai says the bus can travel approximately 186 miles on a full charge. Getting to 100% battery happens astonishingly fast — Hyundai quotes 72 minutes to go from empty to full. That might be slow for a battery pack in a car most folks will drive, but it's quick for a massive bus. There's no final combined output, but one electric motor is used for traction and makes 322 horsepower, while the other motor reportedly attempts to minimize the loss of electricity.
Dimensionally, this bus is large at 42.6 feet long and 13.1 feet tall. It'll fit 70 passengers in total, but most will be forced into the upper deck. Hyundai didn't explicitly say this was due to the massive battery pack, (we imagine it is) but there are only 11 seats on the lower floor to the upper deck's 59 seats. There are also no interior photos, so we're left guessing as to the arrangement inside there. Accessibility features are still present, though. There are two dedicated spots to secure wheelchairs, an automatic sliding ramp and a low floor design to help aid disabled and mobility-impaired passengers.
A rear-wheel steering system is present to help the behemoth get around corners with greater agility. The project itself was supported by the Korean Ministry of Land, Infrastructure and Transport, and began in 2017. There are even active safety systems like lane-keeping assist and automatic emergency braking. At this time, it's unclear when and where the double-deckers will be deployed, but South Korea would be a good first guess.