Vehicles; The Ups and Downs
First and foremost, vehicles are the second most important thing to get, only lower than guns and their respective attachments. Vehicles allow you to move quickly throughout the map and lets you, and potentially your teammates, get to higher ground, inside the circle, reposition to a better location in a gunfight, or just flee a bad gunfight completely. These vehicle choices vary widely and are all useful in different situations. Remember that having a vehicle, regardless of how good it is, is more important than having a good vehicle. For example, a bad vehicle for a squad match, four players on a team, would be only a single two seater vehicle. You could skip out on it and just keep walking and looking for a four seater to prevent leaving other teammates behind, or you could use that two seater to scout in a much larger range for that four seater car. Another option could be transferring one person at a time into the new circle. This is only really needed if it is a later circle that starts dealing more damage, but still an option to potentially save one or two teammates as opposed to you all dying together.
Vehicles in PUBG vary as widely as the weapons. There are over 20 vehicles in the game and they go from a normal offroad SUV to a Motor Gliders that let you fly through the air. Cars spawn everywhere, for the most part. They spawn most commonly in garages and always have at least half a tank of gas. The most interesting car by far is the electric bus that lets you quietly go around the map with, weirdly enough, 6 seats, even though you have a team max of 4. UAZ, or the offroading SUV, is the most popular option as it is a large 4 seater with a very solid body that allows teams to play behind it. Following this is the Coupe RB, which is the fastest car, though its downside is that it has only two seats. The largest outlier to the rest of the vehicles is the armored BRDM-2, which is not only heavily armored but also able to drive through the water. The BDRM-2, though, has the worst mileage per gallon, it also has to be specially acquired through shooting a flare in the air while you are outside the circle. All in all, all vehicles are useful though each has their quirks and all vehicles have their situations that are good.