The eTorque hardware is similar to the setup that's under the hood of the Ram 1500 eTorque, but mated to a smaller four-cylinder engine instead of a V6.
The eTorque system uses a traditional 12-volt lead-acid battery for the accessory and infotainment systems, but it is charged from the 48-volt system via a DC-to-DC converter, since there's no traditional alternator.
The combustion engine in question is a 2.0-liter, turbocharged I4 mated to the Wrangler's familiar four-wheel-drive system and an eight-speed automatic transmission.
My four-door Wrangler eTorque Unlimited claims up to 22 combined miles per gallon, which breaks out to 22 city and 24 highway mpg. I'll save you a Google search -- that's 4 more miles per gallon in the city and 1 more on the highway than a comparably equipped Wrangler V6.