How exactly do you make a car faster?

For example, a Honda civic? A mustang?
Also does it matter whether a car is 2 or 4 door when you're trying to make it fast?

You could put a bigger engine in and/or super/turbo charge it.

HI, IT DEPENDS ON THE CAR AND IT'S AGE. A CARBURATED CAR CAN INCREASE POWER BY ADDING A BIGGER CARBURATOR, CHANGING THE FUEL MIXTURE RATIO, ADDING BIGGER EXHAUSTS. A MORE MODERN CAR, YOU CAN ADD A SUPER CHARGER OR TURBO IF IT'S AVAILABLE FOR YOUR CAR. YOU MAY ALSO BE ABLE TO BOOST PERFORMANCE BY CHANING A COMPUTER CHIP IF THERE'S ONE FOR YOUR CAR. CHECK WIITH A SPEED SHOP, MECHANIC OR AUTO PARTS STORE. LASTLY, YOU CAN CHANGE THE ENGINE AND REAR END IF THERE'S A COMPATIBLE ENGINE AND REAR END FOR YOOUR CAR. ASK A LOCAL SPEED SHOP FOR MORE OPTIONS. GOOD LUCK. REMEMBER, THE MORE POWER, THE MORE FUEL.

It doesn't matter the car you just have to up the power ad a turbo charger or do an engine swap but if your on a tight budget a quick way to ad speed is to take out excess weight to increase the power to weight ratio.

Doors matter not. Drop a large V-8 under the hood with a GMC blower and fuel injection atop it. Fill the tank with 'nitro', buckle up and put the pedal to the metal.

It's all in the engine and aerodynamics. So obviously body work, possibly convert or install a new engine.

The lighter the car, the easier it goes fast!
So shop for cars by horse power by pound!
Often if there are two door models and four door models the two door model will weigh less.
The cheapest path to performance is weight reduction.
The second is a bigger engine.
From there on it gets expensive and is limited only by your research ability as well as your pocket book.
Rule of thumb- it costs an average of 70 dollars per horse.

It depends on the car and the age, and the engine, for muscle cars, I'd say get a super charger, for a tuner, get a turbo kit but make sure it is tuned by a professional