My Fazua Ride60 mid drive has about 80% efficiency according to the manufacturer. It's on a Cervelo Rouvida 1x, 12 speed. It has three power profiles that can each be customized with a maximum power after a specific rider power input and and an acceleration rate for each profile. The battery is 430Wh. Max continuous power is 250 watts with up to 450 very briefly. How long the battery last depends on the needed assist. I've ridden 103 miles with 8740 feet of climbing and still had 9% left, but the easier parts of the ride used a profile that only added 80 watts after I input 120. It consumed less than 1% per mile. Climbing a 10% grade can consume up to 4% per mile, if the profile allows 200 watts. I only weigh around 135, so it doesn't take as much power when climbing.