Although many people would like to drive more fuel-efficient vehicles, most of us have to wait for the large vehicle manufacturers to mass-produce affordable cars that run on alternative power. In the meantime, a handful of smaller companies have begun taking the energy crisis into their own hands. By retrofitting hybrids like the Toyota Prius with a second battery pack, they´re converting these cars into hybrid plug-ins that can recharge from a wall outlet and drive a short commute on all electric power.