 Some dealers assign seasoned sales people as plug-in experts, many of whom drive plug-ins themselves to learn and be familiar with the technology and relate the cars' benefits to potential buyers.The study concluded also that carmakers could do much more to support dealers selling PEVs., the U.S. average concentration was 1.51 plug-in cars registered per 1,000 people, while California's concentration was 5.83 registrations per 1,000 people.