A typical Paris trip is 2 minutes walk to a station (at most 5 min if you are slow), then 30 to 45 minutes subway, then 2 more minutes walk to your destination. There are subway station roughly 2 minutes from anywhere in Paris, and you can go from anywhere to anywhere else in about 30 to 45 minutes. During rush hour, subways are every 2/3 minutes on most lines. The highest time you have to wait is 10 minutes during "dead" hours when going somewhere there is a fork.
It will take about the same time by bike or scooter. But if you choose to take a car? At least the same time, and it can easily be double or triple the time depending on traffic. Then you have to park, which is expensive.
Note that for suburbs to Paris trips, very few people take scooters, because then you have to carry it in the suburb train. Most people will either take a bus to the train station, or take their car and park at the train station (not drive to Paris, that would take double the time).
Now again, I'm only describing what I know about Paris and its suburbs. It's a very different situation in other places (since I'm pretty sure the scenario you're describing is one you lived)