part of the problem is wasted space and money in cities for parking (and, to a certain extent, gridlock). i do own an old, bottom of the line car which i drive rarely - mostly on weekends out of the city as i usually cylce or take public transport. so it often occupies a parking spot 24/7 for a week or longer. on-street parking takes away a lot of spaces that's urgently needed for bike lanes, bus/tram exclusive lanes, walking and green spaces.

there's a good option for car sharing in vienna (car2go), but that's mostly inner-city iirc, so not my use case.

i guess, car sharing wouldn't reduce grid lock but ride sharing would. i suspect, ride sharing would be more acceptable if it wasn't your own car.