Trikke Tech (from California) has three models of Stand-Up electric vehicles that are very portable (fold for transport), and efficient that can still be propelled when the battery is discharged.
Pon-e LITE 36v = primary HPV with electric 'assist'
38lbs. ; 180W motor ; 10mi. range
Pon-e 36v = standard commuter vehicle
42lbs. ; 250W motor ; 16mi. range
Pon-e 48v = commercial version
46lbs. ; 350W motor ; 24mi. range