The average is still 1.3 person per car, if you get outside a little you will see tons of single person in cars, and not in minitruck like artisans.
https://www.paris.fr/pages/le-bilan-des-deplacements-a-paris...
Indicate 13% of the traffic is for utilitary vehicule. This number include people taking their utilitary vehicule for personal reason. 50% is for personal vehicules.
Also, why were you driving around Paris ?
> most alternative routes usually take longer
It depends.