First order of business: don't wear a seatbelt. Your odds of survival drop drastically.
If you can disable the airbags, do so.
If you have an old, heavy vehicle --the kind rednecks proudly declare as having "real steel!" in them-- that improves your chances of ctb.
If you have an SUV, your odds of ctb improve, too.
An old SUV of "real steel!"? So much the better.
That said, it will almost certainly not be a peaceful or quick death.
25 years ago I was a firefighter/EMT in a rural district with icy mountain roads, and within the department I specialized in "vehicle extrication" (cutting people out of wrecked cars) and high/low angle rescue. I've cut a lot of people out of cars. Assuming seatbelts were being used, new cars were astonishingly safe. I've rolled up on cars that looked like Baby Godzilla's chew-toy and after a little work with the hydraulic cutters had the occupants walk away without a scratch --literally not a scratch. It's mindblowing.
Old cars? You're toast. You start off maimed and gurgling, and maybe you die in the ambulance on the way to hospital, maybe you're just fucked up for life. It's kind of a flip of the coin.
At that point I drove a '57 Willys Wagon --the ancestor of the Jeep Cherokee-- and until I was trained in Extrication I thought I was driving the safest car around --it was built like a tank, with real steel! After I got trained, I came to prefer my beloved's Geo Metro. Fuck real steel, the Metro was infinitely safer.
The short version of the science: in a crash, something has to absorb the force of impact. In modern cars, it's the crumple zones, as well as that the modern, thinner steel crumples easily and dissipates the force by deforming. Also, the generally lighter weight of a small car means there's less inertial force to be absorbed for a given velocity. Older, more rigid cars, and in SUVs that have tubular frames instead of unibody construction, their stiffness means the force will be absorbed by something else. That "something else" ends up being the humans in the car.
Anyway, I considered ctb with my car --that old Willys-- several times. It wouldn't do more than 80mph (down hill, with a tailwind), but I had picked out an overpass pylon that wasn't shielded by concrete crash-deflectors. It might have worked, but it did take a lot of pre-planning, and it wasn't a sure thing. If you can find such a head-on compatible crash object, you've got a chance, but it won't be any fun, and you'll have plenty of time to flinch.
And just because I have to put it in: rolling up on a "juicy" wreck isn't any fun for the first responders. Especially not before Christmas. In fact, it sucks.
