Yes, assign the cheapest car to the teenage, however, ......

it may have more doable way to lower the premiune if there are three vehicles. The insurance told me one can be muti cars primary driver. Thus, dad is both of car A and car B primary driver and mom is car C primary driver. The car B is for pleasure and then assign the car B to the teenage for driving the most (but not the primary driver). Of course, the car B should be the cheapest. How do you think about this strategy to lower the teenage car insurance rate or you may have other straegy?