If you don’t plan to visit places along the way the fastest way from Rome to lake Como is a high speed train, not a plane. A train can travel from Rome to Milan in less than 3 hours, city center to city center. With a plane nowadays you need 3 hours just to get to the Rome airport, check in, go through security, and wait to board at the gate. If two people leave from Rome at the same time, one on a plane and one on a train, the one in a train reaches Milan before the other person takes off from Rome airport.
I also don’t think you need a car at all to visit lake Como. You can take a commuter train from Milan and be at the lake in one hour. With Milan’s traffic it’s impossible to do the same by car.
For Switzerland it really depends on where you plan to go, but trains would likely work better there as well.
If you plan to visit places along the way, a car might be useful for visit the countryside and the small towns in Tuscany. However it really depends how many days you have at your disposal between Rome and Lake Como. If you don’t have at least 3 days, there isn’t much you can visit, because the drive is too long.