There is really no such thing as a car that cannot be turned into a hot rod. If you have enough money it is possible. One of the key components to a successful hot rod is the engine. A V8 engine is a must. A stock engine will not do though.
A very popular modification is to add a supercharger (or blower). This is a belt driven device that forces more air into the engine. Mixed with that air is more fuel. This makes for a bigger and more powerful explosion in the combustion chamber thus creating more horsepower.
Other engine modifications will be needed as well. You can't just bolt a blower on a stock engine. Things such as a new camshaft, intake manifold and lower compression pistons must be used. There is also the option of using multiple carburetors or fuel injection.
The engine isn't the only thing that needs upgraded. The stock transmission will not be able to handle the extra power of the modified engine. While some of the die hard hot rodders will stick with a four speed manual, most will opt for an automatic. The automatic really is the better way to go for straight line performance. The shifts are much quicker than doing it by hand.
The other major component that needs upgraded is the rear end. The differential will need upgraded gears to handle the additional horsepower. Also it is wise to shorten the axles. This is a good thing to do for two reasons. First, the shorter they are the stronger they are. Second, with shorter axles, and modifications to the body and frame, you are able to put much wider tires in the back and still have them fit under the car as opposed to sticking out the sides.
Hot rods are a very fun hobby for the car enthusiast. It is a very expensive hobby though. But for those who enjoy it, it is a passion they cannot live without.