Traveling By Private Car between Assisi and Florence

How many is 'we'?

Suggest asking your hotel/ lodging host for a reccommendation.

Probably north of 400euro, for a car that can handle 3 comfortable. If you have more bodies and need a van, expect to pay more.

Check rates on
daytrip.com

ETA
(Lowest quote for random day in September is $635)-it is a 2+ hour drive- really not much faster than train

Are you sure you can’t make the train work?

I see several journeys about 2.5-3 hours with 1 change
That seems totally doable and these are inexpensive regional trains that don’t need to be purchased in advance
Departures almost every hour 16.95 euros

Are you searching on the official Trenitalia site?
https://www.trenitalia.com/en.html

There's just two of us.

In the afternoon there are a few regionale trains doing the trip in 2.5 hours with no changes. Do not believe that with a car will be much faster; I guess it could take the same time.

When in September? There are works planned during the first week of the month, but after the 7th there is a direct R train that departs from Assisi at 11:24 AM. It runs 7 days a week.

On Sundays, there is an additional direct R train from Assisi at 9:25 AM.

There are 8 trains a day requiring no train changes.
Then there are 9 trains a day requiring one change, at Terontola.
Trains take from 2 to almost 3 hours, depending on the train you choose, but on average they need 2h30m.
A car, even a Ferrari, will need at least 2h30 min to cover that distance, assuming no traffic. So actually some trains will get you there faster than a Formula 1 Ferrari with Lewis Hamilton driving.
So I am not sure which trains you are looking at. Yes it’s a lengthy trip, but the only faster alternative is this transfer service from Perugia company. It’s a bit pricey for my budget, but maybe it fits yours.

So I am not sure which trains you are looking at

Well, they might have entered a day of travel on the 1st week of September when, by the current schedules, none of the direct trains you have mentioned should run.

Thanks for all the advice. I was using the italiarail.com site which was only showing a regional train at 5:00 AM and we want to spend the morning in Assisi. It looks like from the advice below I should be booking all the trains on trenitalia.com ? I am planning to purchase all our train tickets online before we leave for Italy.

yes, Trenitalia will tell you the full story. They run the actual trains. The company you were looking at is a reseller who may or may not give the accurate complete offering.

when using Trenitalia you do need to spell the Italian names in Italian. For example Firenze, not Florence, and the main station in Florence, Santa Maria Novella, is Firenze S.M.N.