It isn't economical, but I'm a big fan of the RAM Mount line. My Ford Edge is my office, and I depend on it all day, every day. The laptop is held securely, but comes out easily. It's adjustable, so I can have the laptop right where I want it, or push it out of the way.
My prior vehicle was a Ford Freestar. When I changed cars, all I had to buy was the steel plate that attaches to the seat mounting bolts.
Yeah, it is expensive, but consider what it would cost in time and effort when your laptop crashes to the floor in a panic stop. In my case it was $200 for a new hard drive, and two days of lost productivity.
Rick