It didn't seem THAT bad. Our most recent rental was Peugeot 5008, which was pretty large, and we did alright.
We're going to have two cars, though. One larger, nicer car and a second smaller hatch. We need four doors, though.
when you ask "too large to handle in a city" what exactly are you doing in that city ? street parking close to shopping areas is either very expensive or prohibited in most large cities these days, and free spots are often extremely rare.
Parking in a parking garage is less of an issue (apart from really busy days), just prepare to move backward and forward a lot if you drive something with wide tires
In general something like an A6 is no issue if you live in the suburbs and park in a parking garage when you visit a city, but if you're actually living in the city center you might end up parking a long way from home ... (assuming you have no private parking spot)
but then again like Onkel said even with a Golf you'll have that issue, and if a 5008 was OK I don't think an A6 would be problematic
Also, parking on the streets in French city centers = scratches & dents everywhere eventually