This type of car lift gets its name from its four support posts. However, the defining feature of these lifts is the bridge jacks. Vehicles can drive on and off of these long metal supports, and as long as all the wheels are on the supports, the weight is balanced. This skips the arm adjustment involved with two post lifts, greatly reducing the time it takes to get the vehicle on and off the rack. However, this setup keeps the vehicle on its wheels, restricting access to suspension, brake and drivetrain components.

What are they used for?

There is enough space between the bridge jacks to access most underbody parts, including exhaust, drivetrain and fuel systems. Sometimes these are used for lube service in place of pits. Heavy-duty truck lifts have a catwalk for access to the engine while the truck is in the air.

Alignment racks are a variation on this design: They add rollers and measuring equipment to the rack, but can still be used like a regular four post car lift when needed.

Jack tracks between the bridges can hold jacks, trays and other accessories. This makes transmission work easier, because the gearbox can be rolled forward and backwards along with being moved up and down, making it easier to line up with mounts and bolt holes. In some cases the transmission can be fixed on the jack.

New lightweight models have entered the market, aimed at consumers who need to get the most of their garage space. One car is held on the rack, leaving space underneath for a second vehicle. High lift versions leave enough room underneath to park an RV or conversion van.

What are the disadvantages of these lifts?

A four post car lift takes up far more space than a two post design. Expect a four post version to be three to four feet wider than the equivalent two post lift. Four post lifts may have a lower quoted minimum height than a two post lift, but this doesn't take into account the height of the vehicle. In practice, the usable height will be about the same.

Lowered vehicles and ground effects can pose a major problem when getting the vehicle on the rack. The ramps leading to the bridges may be too steep for the front bumper or side sills, while the bumper lip can hang on the rear support beam. Some older designs included low lift jacks inside the bridge jacks, allowing the vehicle to be lifted off its wheels. However, these have fallen out of favor as their wide surface area guarantees weight will be put on step rails, ground effects, and other structurally weak parts.