I asked this before, but less directly.
So here is very direct.

2000 Audi A6 Rims size is 6.5Jx16 ET48 Bolt pattern 5x112
1996 E300D Rims size is 7.5Jx16 ET41 Bolt pattern 5X112

So the Audi Rims are 1" skinner, but the offset is 1/4 inch more.
Will AUDI rims fit around the calipers?
Will I need spacers? Shorter/longer bolts?

Will the thinner tires make the ride crappy?

https://www.rimsntires.com/specspro.jsp

Online Wheel and Tyre Fitment Calculator. Offset, Tyre Stretch and Speedo Error | Will They Fit

I'm not sure about the caliper fitment, but you'll definitely need at least hub centering rings. Luckily the Audi bore is larger than the MB because otherwise you'd have to bore out the hub to MB spec.

As for lug bolts, that's something you'll have to measure. And if the Audi lugs are larger than M12 you'll need conversion lugs.

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Hopefully you didn't already try this, I just happened to come across this while browsing...

For the future: Actually, Audi/VW is always going to be 57.1 on the center bore until a lot more recently (and only Audi specifically, VW is still the smaller size). As far as I know Mercedes has stuck with 66.6 all along. I looked into getting some of the VW Heritage rims that come on the newest Beetle and I was definitely going to have to mill out the centers. You'll definitely want to research it yourself before someone on a forum says it'll work and you spend a bunch of money on it.

-Rog