Part of the check ride should be practice on things like cornering, braking, and parking, as well as other driving fundamentals. This is where the department's driving instructor can really use his or her creativity to develop methods for measuring and tracking performance.
The ongoing training program should be supplemented with roll call training and training memoranda, as well as occasional reviews of the department's policies, and periodic legal reviews. Of course, officers' participation in all these things should be adequately documented.
A program like this can really pay off in many ways. Beyond bolstering the defensibility of the department's driver training program, it will also be an ongoing reminder for the officers as to the need for care and professionalism in their operation of department vehicles.
Your people are already practicing their driving on a daily basis. Why not make sure they're doing it correctly, and then get credit for the training and practice that your department is already paying for?
Stay safe, and wear your vest! (and Buckle Up!)