What is the driving time in a car from Zamyn-Uud to Ulaanbaatar?

I'm in the border town on the Mongolian side near China. Tomorrow I intend to look for a car to take me to the capital, Ulan Bator.

But when I use my usual tool, Google Maps, to see how long the drive is, it tells me 19 hours, 25 minutes for the 841 km trip.

Now I know there's no German Autobahn covering the route, but according to WikiVoyage, work on upgrading the road was just completed earlier this year.

So is this travel time more or less up-to-date or has the recent roadwork improved it dramatically?

(I noticed Google Maps seemed to overestimate driving and public transport times over the border in Inner Mongolia, China too.)

Oh and I don't expect some kind of magic exact time. Just something quotable from personal experience, found on a blog, etc. I Googled and haven't found anything yet ...)

My experience

As I hitchhiked two heavy (slow) trucks with some long stops for repairs I gave up on trying to add up the driving time. For me it took about a day and a half with some great adventures along the way. Smaller vehicles passed us going very quickly so their driving time could be quite short.

The south part of the road is brand new between Zamyn Uud and Choir, though the south end has some closed sections and doesn't lead to the centre of town where the train station and border crossing are. I don't know where it actually goes.

The north part of the road from Choir to Ulaanbaatar is a few years older and already has some very worn out patches, which makes it slower. It also had some areas with snow and/or ice, but not too much.