a bug-out vehicle (BOV), is dependent on what you specific needs may be because of whatever the situation may be.
you might need a :
cargo van or passenger van to transport relatively large amounts of people or concealed cargo at one time. ex., Chevy Express van or Ford E-series or similar
fuel efficient car to get out of town on regular roadways and go as far as possible on as little fuel as possible. ex., Honda Civic, Toyota Camry, or other small 4cyl powered economy car with approx 30+mpg. modified with either a larger fuel tank or an auxillary fuel tank as vented fuel cans are unsafe in the passenger compartment and screams steal me if you mount them outside.
fast car if for some reason you might need to get away from someone or something really fast and have roads. ex., corvette, camaro, mustang, muscle car, or basically anything modified performance-wise.
off-road capable 4x4 truck/SUV to take you off the beaten path and be able to carry "some" cargo. ex., K-5 Blazer, Ford Bronco, 4x4 full-size truck, or similar.
dirt-bike if you need maneuverability and relatively high speed off-road. ex., Honda other popular serviceable dirt bike.
street bike if you need maneuverability and high speed on roadways to weave in and out of traffic etc. ex. popular sport bike (crotch rocket) or even a cruiser (Harley-type) will work. extra gas on board if possible.
or maybe something else suits your situation better? remember to always keep whatever you use in top mechanical condition and at least enough fuel handy to make it to your BOL (bug-out location). you need somewhere to go BEFORE you leave.
EMP proof or resistant is to be taken into consideration. mechanical fuel injection or carburetor and mechanical igniton is needed.