Yes done many - been a while since took the kids (on account of them now being young adults) but I think it's doable if you are careful with your budgets.
Germany is pretty reasonable (except petrol) even with the current exchange rate, and central France is too away from tourist hot spots - always fill up your car at French supermarkets before heading east as they are the best for fuel, or use total energies fuel stations. I'd avoid Switzerland to be honest, it's easy to do so, just stick on German side of the lake, as their motorways require an annual permit, also don't drive on Austrian motorways for the same reason (Germany doesn't charge, France and Italy are tolls for what you use but in France just stick to the N roads and they are free.). I tend to stick to a max of 6 hours driving in a day and then book 2 nights in one place. You'll get brownie points off the kids if some hotels have pools eg holiday inn often has a good family rate.
My tips - booking hotels ahead gets good rates but you can grab same day bargains, always look on google naps for little independent ones that you won't find on booking.com or similar for great places (eg I paid £52 for a room (for 2) including breakfast AND evening meal last year at this little roadside restaurant with rooms in france near Swiss border, even gave us complimentary wine.
Booking b&b usually is your best bet, let the kids really fill up then stop at a supermarket at lunch time and buy bread, cheese etc (I always pack picnic blanket, bread knife, cheese knife, buttering knife, bread board, some plates, forks, tin and bottle opener etc) as well as fuel.
If your car fit them, each having a suitcase worked for me, even at 5 mine would drag theirs in. Don't forget the dirty washing bag in each too. Bring 2 toothpastes if sometimes the kids will have a separate room (forgot myself once they got to the age they didn't always share with us)
I would look at incorporating europa parc into your itinerary, my kids loved it (it was part of Tesco club card scheme then too). I've clocked tens of thousands of miles on road trips with mine, it's a great way to show your kids the world, and since they grew up we go on the motorbike instead.