I'd like to know the answer to this question too because we're going in the fall. I have read somewhere that there are moving sidewalks that take you from the parking garage on the south side up to the old town area, but I don't have the exact location of the parking area. Let's hope someone does.

Here you go:

http://www.microsofttranslator.com/bv.aspx?ref=SERP&br=ro&mkt=en-US&dl=en&lp=IT_EN&a=http%3a%2f%2fwww.umbriamobilita.it%2fit%2forari%2fascensori-funicolare-scala-mobile%2fspoleto

If the translated link doesn't come through, here's the original page:

http://www.umbriamobilita.it/it/orari/ascensori-funicolare-scala-mobile/spoleto

Double-check your GPS route as many (most?) streets are one-way.

You can also parking at/near the train station and walk. It would be about 2 kms. to the top of the town.

Thank you Jean - I have been looking for a while now and coming up empty - found that site but didn't know how to translate that page. It did come through for me translated.

Here is a mappy that shows the "Spoletosfera" parking garage with the escalators - I had to scroll to the right to find the parking garage on the map. But no gps details.

http://mappery.com/map-of/Spoleto-Map

There is also a trip advisor question in the forum section on this topic - I will try to link that here in another post.

I don't know if this is the "better" parking garage - because I haven't been there yet - not until October - but here is the trip advisor link:

http://www.tripadvisor.com/ShowTopic-g194924-i2362-k5442807-Parking_lot_Escalator_Location-Spoleto_Province_of_Perugia_Umbria.html

I think davispeets' mappery link is not on the usual North-South axis. I think it's about 90 degrees off, but do check for yourselves.

Just FYI, we found Via Martiri Della Resistenza (bottom edge of davispeets' link) a very easy way to approach Spoleto from the north (SS418/SS3). Our hotel was on the parallel road Via Interna Delle Mura. Martiri (two way) is outside the city walls, and Interna (one way) is inside the walls. There are openings periodically to allow traffic to switch between roads. We would turn left off Martiri at the first opening (Posterna?) and immediately turn right onto Interna. It's hard to tell from any of the maps and links exactly where to enter the parking lot in that area. The lot and escalator were under construction when we were there, but they are definitely within the city walls.

BTW, Via Della Posterna becomes Via del Trivio as it goes up the hill. Osteria del Trivio at #16 is a very good family-run place.

I think Jean is right that the mappy referred to in one of the links above is not straight north-south wise. I was able to find the underground exit on Google maps, and I think I have the GPS coordinates. I'm not sure because I've never tried using for these before, but this is what it came up with:
42.730433, 12.733687

I hope that helps. I'm going to be trying to find this same parking ramp in a few months so I hope it works for both of us.