Buggies are the biggest introduction in Dying Light: The Following and, as they have a great role in the game now, it is important for you to have a great understanding of them and the way they work.
First, you have to know that Techland has made buggies highly customizable, meaning that you can change the way they appear but also the way they behave. Buggies have these upgrades possible: suspensions, brake system, clutch, turbines and engine.
Those parts can also be damaged when you make a heavy use of buggies. To repair them you can buy Bolts, usually sold three pieces at once, or find them in the loot. You can repair a part of the buggy only three times; afterwards you will be required to buy a new part.
To upgrade, instead, you need specific drawings and details to be found in chests. You can open those chests with a red card you will find throughout the story missions. Upgrades have a maximum of six levels. You can also customize your design applying colors, decals and accessories you will find in loot.