why do cars need streamlining???

Better gas mileage for one. The less resistance to the wind they cause the better gas mileage they will achieve. Also l guess to be appealing to the consumer is eye!

l reduce wind nose and wind drag. You use less gas if there is little wind drag.

Put your hand out the car window--palm front. Feel the drag? Now turn it palm down. Much easier huh? You have just streamlined your hand and reduced drag.
If your hand were a car you would be saving tons of fuel.

LESS RESISTANCE FROM WIND TURBULANCE = BETTER GAS MILAGE.

this is just like free falling from sky
if you have a parachute it makes ur fall smooth without harming you. else you will slam into ground.

similarly if your car is well streamlined it will have minimal wind force againts its motion so it can give better performance ( quick fast and more efficient)

same as the ford lightning and the ford gt have the same engine block but the ford gt is a amazingly fast machine.

to have an excuse to make the car a little different so you can keep selling new and obsoleting old.