We drove from the Hertz place near Gare Montparnasse, to the Peripherique, and on to Bourges, on a weekday. It went fine, required plotting the route in advance, then a lot of attention from us both, I'd suggest using the Via Michelin website to get your best route. Google Earth can also route you, and its street view can show you what the landmarks and turns look like. GPS should help too, though we didn't have it on the trip from Montparnasse. Drove back in a couple of weeks later with few problems.
Driving in Paris isn't fun and isn't a good way to get around the city itself, but driving in and out is certainly doable. And Gare Montparnasse is close enough to the Peripherique to make it worthwhile.