Car or no car for 7-8 days in Slovenia?

Hello forum, we are a couple in our sixties planning a 2 week trip Budapest- Slovenia, with the probability that it will be 7-8 days in Slovenia, likely from June 20th. I am thinking of taking public transportation from Budapest to ljubljana, and then renting a car for travel in Slovenia...we are easy nature walks, nature in general. I have my eye on the Julian Alps as well, however...I don't fancy driving the high mountain roads, not comfortable with that.

I am wondering if it would make sense to leave the car in Bled or for 2-3 days and use other kinds of transportation to move around the Julian Alps? Itinerary is still open- interested to hear suggestions- thanks very much!