Cell Phone Driving
The Mythbusters wanted to test out whether driving drunk is better or worse than driving while talking on a cell phone. They went through a closed course to test out their theory, and found that talking on a cell phone was actually worse than driving drunk. To be fair, they didn't go past the legal limit, so a severly drunk person will surely fail horribly, and likely even worse than the cell phone driver.
Pickup Truck Tailgate
A lot of people want to know if they can increase their fuel efficiency by putting their truck's tailgate down, or by putting a cover over the top of their truck bed. It turns out that neither of those things matter. The Mythbusters found that what will increase your fuel efficiency by a little bit is replacing the tailgate with a mesh gate.
The myth is that a car cannot be sold, even at a good price, if something died inside of it causing it to smell. The Mythbusters did everything that they could to remove the smell including a deep cleaning, replacing the entire car lining, and it STILL smelled. They couldn't sell the car for anything but parts, so this is completely true.
Rear Axle Removal
In movies, cars will often have their rear axle ripped off when they are attached by a chain or cable to something. The Mythbusters did everything they could to help the process along including loosening the axle bolts and finding a super-strong chain, but the axle didn't break. Turns out the movies exaggerate, as always.
You might have heard various urban legends about ways to beat the cops' radar guns to avoid a speeding ticket. Unfortunately, no matter what the Mythbusters tried, ranging from mirrors to aluminum foil to new paint jobs to other illegal methods, nothing worked to stop the radar gun.
Anxious drivers worry sometimes about whether a truck tire might explode next to them, and also whether or not an exploding truck tire could decapitate you. The Mythbusters had to set up the exploding tire perfectly to get the right result, but they did find that a piece of tire going 40 mph at your head would most likely decapitate you.
If you're about to hit a moose or a deer on the road, should you hit the brakes, or will speeding up cause the animal to flop over the car and cause less damage? Well, the result is exactly what you should expect: braking and slowing down causes less damage, and when speeding up the Mythbusters found that it just caused more damage, even if the animal does hit slightly higher up.
Rain Drops Aren't Falling On Your Head
When driving a convertible, should you stop to put your top up if it starts raining or just speed up to keep the water out? Well, the mythbusters tried both methods, and found that you definitely get pretty wet when you stop to put your top up. On the other hand, if you speed up to over 70mph you can have little to no water land inside the car at all! Unfortunately, you definitely shouldnt go over 70mph when it's raining, so you might as well put your top up and live to see another day.
Fuel Efficient Dirt
Does a dirty car act like a golf ball and increase fuel efficiency? Apparently not. Dirt is too random and sticks out, increasing drag and reducing fuel efficiency. But the Mythbusters actually created a car body that has dimples like a golf ball and found that it Does in fact increase fuel efficiency!
Car Off A Cliff
To examine yet another movie myth, do cars falling off of cliffs explode? The mythbusters tried everything they could to get it to happen, including putting the gas tank in the front of the car to get it crushed, but nothing happened other than a bit of a fire.
Car In Water
Most people know that a car sinking in water can be extremely dangerous, but the Mythbusters wanted to test just how long it takes to be able to open your car door when it is sinking. They found that a normal person would not be able to hold their breath long enough to wait for the pressure to equalize and be able to open their car door normally.
Yet another movie myth that people believe is that shooting a car's gas tank will cause it to explode. This seems plausible at first, since guns are explosive, bullets move fast, and you'd think that maybe some sparks would fly. However, the Mythbusters did a test where they unloaded tons of bullets into a gas tank, and the tank never exploded or even caught fire.
To AC or not to AC
It takes energy to use the air conditioning in your car, so the Mythbusters (as well as many car manufacturerers and Consumer Reports) want to know if it's more efficient to drive with the AC on or simply with the windows down, increasing drag. According to every test these groups produced, the AC always uses up a bit more fuel. It seems that in cooler weather, it would be best to just roll the windows down, but if it's too hot, simply using the AC won't cost you much more at all, and you'll be much more comfortable and safe.