One of the roadblocks to mass production of any non-gasoline based car is that manufacturers are not willing to build them without infrastructure, and infrastructure does not get built without the cars to use it. In order to bridge the gap, transitional technologies are being used, like hybrid vehicles and plug in hybrids on the way to electic vehicles, and blended ethanol and biodiesel for others.
Fortunately, some progressive companies, like Tesla Motors, are still building EVs and some cities, like San Francisco, are beginning to install more infrastructure. However, it’s definitely not enough to have a national impact. One concept that some ports are now implementing, like Los Angeles a while ago and now Long Beach, is to allow (and eventually require) cargo ships to plug into the grid while docked. This improves local air quality and reduces fuel consumption. The same concept could be applied to other vehicles on land.
I am not aware of any specific data, but from personal experience I have seen tractor trailers, buses and RVs idling overnight at highway rest stops so they can run the internal climate systems. There are even regulations requiring rest after long shifts of driving, which add to the problem. Some of these also have stand alone generators that are more efficient, but they still burn fuel.
Many RV parks do provide access to the grid for longer trips, but I have not seen (or really looked for) plugs in highway rest stops. Most of these vehicles already have the ability to run the internal systems on electricity only from the batteries, so adding components to allow them to plug into the grid would not be difficult. There would even be incentive to plug into the grid because running on electricity will be cheaper than powering a vehicle by keeping the engine running, especially over long periods of time.
I found out on a recent trip when waiting for a tour to start, in Rome, there are even regulations limiting how long buses can be idling within the city limits. There are enough buses that it has a noticeable impact on air quality in tight quarters. However, US rest stops are spread out enough that it does not appear to be a concern. Total emissions and fuel consumption, on the other hand, are a big problem. Allowing trucks, buses and RVs to plug in at rest stops and other high traffic areas would help reduce emissions and fuel consumption, as well as help build out EV infrastructure. Quick stops will not allow for most EVs to fully charge, but it should extend the functional range and help break down one of the major barriers to EV adoption.