Hi jatrax,
You sound like me in 2007. The subject of tow vehicles had me dizzy, and I think back then it was more straight forward. These days many 4WD and 4x4 types have a convenient dash-mounted electrical switch for the driver to select 4WD high and low, and some don't have a neutral position like the old days when the vehicle had a separate gear shift lever. Our Jeep Liberty has such a mechanical lever. When I put that lever in neutral and the transmission in park, all is well. The automatic transmission is prevented from spinning so it is protected while being towed.
Back in 2007 with exception of all Saturns and other sprinkled brand models it seemed that if you had an automatic transmission, you needed to have a gear transfer case with a neutral position, just like our Liberty has. Of coarse 99.99% of the vehicles sold with automatic transmissions back then didn't have a gear transfer case so they were ruled out. People with most front wheel drive auto-trans vehicles got around it by using a tow dolly. A rare few people with rear wheel drive auto-trans vehicles that stood tall actually went as far as removing the drive shaft to tow their vehicle with all wheels on the ground. People sought after manual transmission vehicles with tow bar brackets offered.
A few vehicles in 2007, but many vehicles following 2007, automatic transmission vehicles were able to be towed with all wheels on the ground, but every few hundred miles, you need to start and warm up the tow vehicle and then go through all the gears a number of times while holding the brake pedal. It seems most recently, the auto manufactures state that if you tow their vehicle all-wheels-down, it voids their warranty.
Now-a-days, many vehicles have push-button start so there is no key to mechanically unlock the steering wheel. Some vehicles, the gear shift lever is actually an electronic devise, not mechanical, so putting the transmission in neutral, it might not stay that way when the car is turned off and being towed. Today's high technology adds more complexity in vehicle choices, hence more research required to determine how (or if) it works when being towed.
There are a few websites out there with charts to show which vehicles are okay to tow with all wheels on the ground. If I were looking for a tow vehicle today, I would seek those charts but not solely rely on them. I would also seek available tow bar brackets from the towing hardware suppliers like Blue Ox and Roadmaster. I would be most confident with a vehicle like our Liberty with a mechanically controlled gear transfer case.
In this picture of a 1st generation Jeep Liberty 2002-2007, you can see the gear transfer case shift lever to the left of the transmission gear shift lever. It resembles a parking brake lever. If you look close, you can see a diagram on it that explains each position. That lever shown here all the way down is in "normal rear wheel drive mode".
