Building a nuclear bomb is not as difficult as many people tend to believe. If you just need something like a nuclear car bomb things get a lot easier. You will need the following ingredients:

required:

4 kg of plutonium alternatively 10 kg of weapon grade uranium
100 g of C4
1500x10cm pipe preferably made in some nice shining metal.
An Old Car
Some kind of timing device

Optional

Rubber Gloves
beryllium sphere


Put just below critical mass of plutonium (2 kg) or uranium (5kg) in each end of the pipe. From now on it is very important to handle the pipe very carefully, no sudden moves and keep it horisontaly at all times. Put 50g C4 (the important thing is that it is that it is exactly the same amount on both end) in each end of the pipe.

fig 1.
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<|C4|Plutonium| ---1.4m --- |Plutonium|C4|
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Optionally you might want to add a beryllium sphere on the middle of the pipe for extra performance.

Carefully move the pipe to the back of your car. Set up the timing device (usually an old alarm clock) to detonate the |C4| charges using power from the car battery.
Congratulations! you now got your very own nuclear car bomb!
Park the car outside the UN headquarter, in the middle of New York outside your local Microsoft Office or any other target you might chose, set the timer and run like hell.

see also: where to buy plutonium, how to hot-wire a car, how to treat radiation burns, How to Make a Decent Bomb Threat, Global Thermonuclear War, and How to survive a nuclear incident