When shopping for a new car or while reading vehicle reviews, you may come across two different construction types, describing it as either a unibody vehicle or a body-on-frame vehicle.
So what do these mean? A body-on-frame design involves mounting the car's body onto the chassis, which holds the powertrain. A unibody design consists of manufacturing the frame and the body as one single unit.
Most modern vehicles, including SUVs and pickup trucks, utilize a unibody design. However, some body-on-frame vehicles are still common; nearly all full-size and midsize pickup trucks, for example, are body-on-frame.
Deciding which construction type is the better option depends on the purpose you want to use the car for. Continue reading to learn more about unibody vs. body-on-frame vehicles.
Unibody vs. Body-on-Frame Vehicles
There are several differences between body-on-frame vs. unibody vehicles. Let's explore each design in further detail.
A body-on-frame design is constructed in two separate parts, namely the chassis and the body. This construction is historically the original design for US vehicles and dates back to the first automotive models ever produced on an assembly line.
These designs included the following:
- Ladder frame
- Backbone chassis design
- Platform frame
- X-frame design
- Perimeter frame
The most straightforward design is the ladder frame, which consists of symmetrical longitudinal frame rails connected by a series of lateral support members. As the name suggests, this design resembles a ladder. It's still found in most full-size pickup trucks and SUVs and nearly all medium- and heavy-duty work trucks.
Because a body-on-frame construction comprises two separate parts, compared to unibody vehicles, they are cheaper to repair and adjust more easily to off-road terrain. They also have a heavier towing capacity due to their sturdy foundation.
Pros and Cons of the Body-On-Frame
Better off-road capability: Body-on-frame vehicles tend to be better off-roaders, as they withstand twisting forces better when driving on uneven terrain instead of paved roads. Body-on-frame trucks and SUVs are also more resistant to dirt, mud, snow, and stones when driving off-road since they typically have a higher ground clearance than unibody vehicles.
Better hauling and towing capability: Body-on-frame vehicles have a greater hauling and towing capacity than unibody models due to their sturdy foundations and tolerance for torsional flexing.
Cheaper to build, repair, and maintain: Another benefit of body-on-frame vehicles is that they're cheaper to build and repair. Because the body and frame are separate units, you can replace one if it gets damaged instead of both. Damaged body parts are much cheaper to fix than an entire vehicle shell, making body-on-frame vehicles ideal for people who are notoriously hard on vehicles, such as law enforcement.
Quieter on the road: Body-on-frame vehicles make less noise on the road because rubber pads around the attachment bolts separate the chassis from the frame, insulating passengers from the sound of the tires.
Better protected from moisture on the road: Their higher ground clearance also protects body-on-frame vehicles better from the moisture of the road, which may lead to rust.
- Heavier than unibody vehicles.
- Have a lower fuel economy.
- Lack crumple zones.
- Provides a rough ride on regular roads.
- Results in more severe accidents.
Examples of Body-On-Frame Vehicles
Some of the most popular body-on-frame pickup trucks for 2022 include the following:
- Ford F-150
- Ford Ranger
- Chevrolet Silverado
- Chevy Colorado
- Toyota Tundra
- Toyota Tacoma
Some of the most popular body-on-frame SUVs include the following for 2022:
- Cadillac Escalade
- Lincoln Navigator
- Ford Expedition
- GMC Yukon
- Chevrolet Tahoe
- Toyota Land Cruiser
- Lexus GX
- Toyota 4Runner
- Jeep Wrangler
Unibody is short for unitized body or unit body. Vehicles with a unibody construction have the chassis and body manufactured as one single unit instead of two separate components like the body-on-frame construction. That means the body, floorboards, primary chassis structural support, and crash-protection elements are joined into a single piece or unit.
Unibody frame designs first entered the US in the 1930s. They quickly became a popular choice for automakers because of their lighter design, higher safety ratings, and the efficiencies that came with the design.
In addition, because unibody frames are more lightweight than body-on-frame designs, they provide better fuel efficiency and are generally easier to drive than on-road vehicles.
The single-unit design means automakers can implement crumple zones into the vehicle's frame. These crumple zones better absorb impact from a collision, which means there are fewer fatalities and injuries in the event of a car accident. Most modern passenger cars and most SUVs feature a unibody frame and even some light commercial vehicles.
Often, unibody and monocoque construction are terms used interchangeably. Still, they aren't the same because an actual monocoque frame gets its strength from the car's entire external "skin." A monocoque design typically relates to a "single-shell" car construction. The entire exterior skin of the vehicle's body is a structural, stress-bearing shell, similar to that of an eggshell. Road and passenger cars technically have a semi-monocoque or unibody-frame design.
Pros and Cons of the Unibody Setup
Easier to design and build: Computer-aided design software allows automakers to mold the shells of cars like clay to achieve precise contours. Sophisticated manufacturing processes produce these shells quickly, despite consisting of several different materials that must be welded or riveted and parts that must be attached.
Better fuel economy: Unibody vehicles are lighter, which means they have a better fuel economy than body-on-frame vehicles.
Rollovers are less likely: The unibody's low center of gravity makes rollovers less likely.
Smoother ride quality: Unibody cars offer a smoother ride on paved roads and have specific points that absorb kinetic energy for a more refined driving experience.
Easier to find: Since unibody vehicles are much more common than body-on-frame ones, finding one to buy is easier.
Higher safety ratings: Unibody vehicles have higher safety ratings because they feature crumple zones, which better absorb the impact from a collision.
- Hauling and towing capacity is not as high as body-on-frame vehicles.
- Off-roading is more challenging in a unibody vehicle.
- Unibody vehicles are more expensive to repair.
- Vehicles with a unibody frame carry higher pricing because of their expensive design and manufacturing costs.
Examples of Unibody Vehicles
Nearly every passenger vehicle uses the unibody design, including sedans, hatchbacks, minivans, crossovers, SUVs, and even some pickups. That includes crossover SUVs, which increasingly featured unibody designs after the Toyota RAV4 arrived in the US in 1996.
Some of the most popular unibody SUVs and pickups for 2022 include the following:
- Ford Maverick
- Hyundai Santa Cruz
- Honda Ridgeline
- Toyota Highlander
- Honda Pilot
- Chevrolet Traverse
- Ford Explorer
Body-On-Frame vs. Unibody: Which One to Choose?
The type of vehicle frame that is right for you depends on how you plan to use it.
Consider a body-on-frame vehicle if you want cheaper repairs, superior towing capacity, better off-roading capabilities, and more customization opportunities.
However, if you want a safer vehicle with better handling and a greater fuel economy, a unibody vehicle would be better.
Perhaps you need a versatile vehicle that combines the two. If you want a family vehicle that can tow a trailer or journey off-road, determine whether the drawbacks of a body-on-frame vehicle are worth it for your particular situation.