With modern vehicles batteries will go dead for lack of use. The vehicle computer is alive all the time consuming a little juice. After a few weeks the battery will be too dead to start the engine.
We have several vehicles with only two drivers. We know it is important to run each one at least once every two weeks.
With this information, this means the PD seldom uses their vehicles anyway. Newer used vehicles will not solve the problem, driving the existing ones will.
I find it hard to believe that they don’t drive their cars at least daily. They’ve got a seven man police force. They must be out cruising for traffic violations and visibility.
Our 700 person town has (I think) a police chief and one patrolman. They are always driving around town, lending hands, keeping an eye on things, writing citations. We depend not the County Sheriff if a police officer is not available.