I first used a tow dolly to tow our 2005 VW Passat behind the '94LY Diesel pusher. I learned to dislike this for the following reasons:
1 - The rear of the car was lowered since the front is raised. Going over a speed bump at 2mph in a campground, the rear fenders touched the ground and caused the bumper to pull away. Cost to repair: almost $1,000.
2 - You cannot appreciate how wonderful it is to either get the car on or off the tow dolly in wet weather, especially since I had to pull out the ramps by getting down on my knees.
3 - Going into a rest area and finding out that the turning circle to get out is too tight - you can't back up with a tow dolly, and if you think removing the car is a hassle normally, wait until you try it when the whole rig is on a curve.
So I researched towing 4-down. I was also considering the option of using a car trailer, but that didn't address the issues of detching or removing the car in tight quarters. So the the 4-down option seemed best. However, I didn't like the idea of having the car brakes controlled electronically, as I knew from my trailer-towing days that adjusting electric brakes to match your load can be a hassle, and I didn't want the little Mazda 323 have it's brakes come on and lock while being hauled down the road behind almost 20,000 lbs of diesel pusher. So I opted for a set of tow bars with a surge brake system built into it. The ones I use are made by Night Shift Auto and are called Ready-Brake - here's their URL: RV Tow Bars and RV Surge Braking Systems for Car Towing - Night Shift Auto