Such a vehicle wouldn't be able to travel on a freeway at all [1], which means the market for them is very limited. Even in cities, people will want to hop on a freeway to cut across town more quickly.
[1] Most states have rules around operating a minimum speed with the flow of traffic, so cars inhibiting the flow or otherwise driving significantly slower than the cars around them are considered to be a safety hazard.
Some states are more objective by posting both minimum and maximum speed limits, though I personally find that freeways with speed minimums tend to actually have more people driving slow enough to cause disruptions.
Today. But, no reason why we couldn’t change the rules to let these vehicles travel in the right lane only. Just as trucks are restricted so on certain highways.
Technically, everyone is expected to drive in the right most lane unless they are passing or there is a left-hand exit coming up.
This would just force average speed drivers into the left lanes and slow traffic down overall, and contribute to more traffic jams as the uneven speeds cause ripple effects.
[1] Most states have rules around operating a minimum speed with the flow of traffic, so cars inhibiting the flow or otherwise driving significantly slower than the cars around them are considered to be a safety hazard.
Some states are more objective by posting both minimum and maximum speed limits, though I personally find that freeways with speed minimums tend to actually have more people driving slow enough to cause disruptions.