How’s about some travel advice…

Probably depends a lot on your other plans, time and budget.

It's a lovely region, if you have time, there's plenty of things to see and do nearby. Is this part of a larger itinerary? If so, where else are you planning to go? How much time/flexibility do you have in your schedule? Have you been around this region much before?

Cost is going to vary quite a bit. I have not looked at specific prices, but rental cars are often shockingly expensive this year -- if you haven't already done so, you should price out what these options would cost you. Pretty sure the rental car would be significantly more expensive than the other options you mention -- though it would give you freedom to explore more of the area. Of course, if you don't have time/interest in exploring more, that could be paying more than you really need to.

Do you have a railpass? If you do, you could consider taking a (longer) night train from Munich to a random city, shorter layover, then another (longer) night train from there to Ljublana. Gives a chance for two decent naps versus spending quality time sitting in a train station.

I haven't taken the FlixBus but we've used other bus companies for transportation in Europe (Spain, Greece, Turkey) and it's been a good experience. The FlixBus is inexpensive and there are several options for departure times throughout the day. I'd be inclined to consider that option!

We used Flixbus in Italy last month, and it worked well. The bus did fill up, though, so if you decide to take it, get your tickets early, and pay the extra euro or 2 to reserve your seat.

We used Flixbus in 2019 among Italy, Slovenia and Croatia. Easy to book on line. Nice modern busses. Very comfortable. And inexpensive.

We used Goodbye last year when Germanys trains were on strike and were found them to be comfortable. We would not hesitate to use them again.

Flixbus not good bye.

Thanks for the input everyone. A little more background. This week in Slovenia will be the last week of a 6 week vacation; Italy, Germany and Slovenia. Our time is flexible with nothing actually scheduled. While cost is always a consideration, I am leaning towards the car rental. I can get a full week compact car for 410 Euro rountrip. Certainly gas adds more $$$ (or should I say Euros?). This gives me some additional flexibility once we get to Slovenia to visit outside of Ljubljana. My grandparents were born in Gorenja vas and Šentlambert so we will want to visit those places in addition to typical newbie sites.

Does anyone know if there mihht be a train schedule update between now and then?

Several years ago, we were travelling from Munich to Ljubljana, and got stuck in Villach for 6 hours. It was a great stop. There is a nice downtown to walk around in, several nice restaurants.

We have used FlixBus several times, and each experience has been good.

This May we rented a car in Italy for a trip that included Ljubljana and Lake Bled (loved both). We appreciated having the flexibility the car provided. Be aware that there isn't a lot of parking in Ljubljana, so you might want to plan ahead.

Good news !

It appears that the "normal" Deustche Bahn train schedule is back. There are now multiple trains each day to and from Ljubljana. Looks like I can do the train as I originally expected.

I wonder why the schedules changed this week .

I don’t know how it works with rental cars (if they will provide you with one) but for Austria and Slovenia you need a toll vignet.