By Andy Jensen on May 13, 2021 in Life Hacks
Let’s say you’re shopping for a new ride and considering a Dodge Charger. You’ll notice it has a lot of options, including a rear-wheel drive (RWD) or all-wheel drive (AWD). You can also find two-wheel drive (2WD) and AWD options on everything from the compact VW Golf to the Toyota Sienna minivan and every pickup truck on the market. Is AWD worth the price increase? Let’s take a look at what 2WD, four-wheel drive (4WD), and AWD systems are; their pros and cons; and which one is right for you.
What is Rear-Wheel Drive?
When you step on the gas pedal, not all your wheels drive your vehicle forward. In most cars and driving conditions, one wheel receives the power to accelerate you onto the highway, while the others are along for the ride.
A lot of parts are necessary to transmit the spinning motion of the engine internals to spinning the wheels and moving your vehicle. Keeping it simple, RWD vehicle transfers engine power through the torque converter and transmission to the rear axle. In between the transmission and axle, the driveshaft runs the length of the center of the vehicle. You may have seen a driveshaft on large box trucks (such as moving trucks), where a metal tube spins as the truck drives away. This tube is the driveshaft, and it’s a big clue that the vehicle is RWD, sending power only to the back wheels.
Starting with the earliest cars and trucks, nearly every vehicle was two-wheel drive, specifically driving the rear wheels. For early car designers who were still trying to figure out the steering wheel, the front engine and rear drive offered a balanced vehicle, simplicity in assembly and maintenance, and a competitive cost.
Early RWD cars let the tires perform separate tasks, with the rear driving the car forward and the front handling steering. All the wheels handled braking. Every popular car, from the first “horseless carriages” through 1960s models, were all RWD. Everything from basic work trucks to Formula 1 racecars ran RWD designs. RWD systems were cheap, easy to work on, and made sense — until gas mileage became a priority.
What is Front-Wheel Drive?
Manufacturers knew RWD wasn’t efficient with a long, heavy driveshaft spanning the distance of the vehicle. It takes energy (fuel) to spin all that metal. As a solution, engineers designed front-wheel drive (FWD) cars.
With FWD, the engine and transmission sit together in a compact engine bay, often turned sideways, to drive power to one or both front wheels. This condensed package skips the driveshaft and reduces weight through smaller and lighter parts.
European drivers consistently had higher fuel prices than the U.S. and prioritized fuel economy when buying cars. By the 1950s, FWD cars such as the Austin Mini (today’s Mini Cooper) were cruising all over Europe.
In North America, FWD cars didn’t catch on until the 1970s when gas shortages led many Americans to rethink driving big-block, rear-wheel drive coupes to do grocery runs. Search for an image of the 1972 Ford Thunderbird for a look at inefficiency. The first Honda Civic debuted in time for the 1973 gas shortage, and the FWD car immediately changed the market. By the late 1980s, most passenger cars such as the Chevy Nova and Pontiac Grand Prix had switched from RWD to FWD for increased fuel economy.
What is All-Wheel Drive?
Around the time cars mostly switched to FWD, Subaru took another route with an all-wheel drive (AWD) system. AWD is a design that combines FWD and RWD, but there’s more to it than that. Like RWD, an AWD car sends some of its engine power back to the rear wheels.
However, AWD cars also have a transfer case sending a driveshaft running forward to the front axles, providing power for the front and rear sets of wheels simultaneously. Driving all four wheels means increased traction in muddy or icy conditions.
AWD saves gas by operating as FWD most of the time, only sending varying amounts of power to the rear wheels as needed. Despite their hilarious commercials, Subaru sales took off once they pushed AWD in cars such as the Outback and Impreza. All-weather capable cars became a cool alternative to big SUVs. Other manufacturers took notice, and AWD started trickling into nearly every manufacturer’s lineup.
What is Four-Wheel Drive?
You’re probably used to seeing four-wheel drive (4WD) advertised in truck commercials, such as for a Ford F-150. Four-wheel drive sounds like AWD, but there are differences. Manufacturers don’t say pickups offer AWD, and it’s not just advertising. AWD systems such as Volvo’s Haldex use multiple sensors to detect wheel slip, and instantly respond with hydraulic pressure activating couplers to add or remove power at different wheels.
Four-wheel drive systems are much simpler, with a direct physical linkage to all four wheels. The transmission evenly splits the power, sending an equal 50/50 to the front and rear wheels. Four-wheel drive also differs in the 4Lo gear, which multiplies torque for low speed, similar to the “L” or “1” on an automatic transmission. Four-wheel drive provides confidence on rough or muddy terrain by driving all four wheels all the time.
4WD and AWD Pros
According to research by the automotive business intelligence firm JADO Dynamics, AWD and 4WD reached 50 percent of the market in 2020. Many buyers want AWD and 4WD for their numerous positive benefits.
- Traction and towing capability
Take a look at the spec sheet for any truck and you’ll notice 4WD trucks usually have a higher tow rating than 2WD trucks. Check the 4WD box when ordering a Chevy Silverado 3.0L diesel, and the towing capacity jumps from 7,600 to 9,300 lbs.
- Dry handling
4WD and AWD selling points often center on its ability to get you through the ice, snow, and mud. AWD systems also enhance traction on dry roads. AWD is a safer way to drive, and safety sells.
Even high-end sports cars now have AWD. The huge horsepower of modern cars can overwhelm two tires, but when it’s applied to four, it makes for a quick getaway. The AWD-equipped Nissan GT-R uses all that grip to launch from 0 to 60 in just 2.9 seconds.
- Resale value
AWD cars have unusually strong resale value, especially in some regions of the country. In the Pacific Northwest, drivers call the extra money you pay for a used AWD the Subaru Tax. Buyers also pay top dollar for used AWD cars during New England and Midwestern winters.
4WD and AWD Cons
Ownership is not all muddy fun. The downsides to AWD and 4WD are minor, but they may bother some owners. Here are a few to expect.
- Lower fuel economy
Extra parts mean extra weight. And 4WD or AWD adds weight to the drivetrain between the engine and tires. You can see this reduced fuel efficiency in the Dodge Charger. The AWD gets 18 miles per gallon in the city and 27 on highways whereas the standard 2WD gets 19 miles per gallon in the city and 30 on highways. AWD hybrids such as the Toyota Prius AWD-e solve the gas mileage problem, but these systems are fairly new.
- Higher maintenance costs
With extra parts comes extra maintenance. That extra front differential in a 4WD truck needs an oil change too, meaning twice the cost for that maintenance task. With some AWD cars, you must replace all four tires at a time to keep the tread depth the same. So if you get a flat in one older set of tires, you need to replace all of them.
- Increased price
Strong resale value only helps the seller. If you’re a buyer, it’s a con, as you’ll have to pay more.
- False sense of security
It’s all-wheel drive, not all-wheel stop. AWD and 4WD don’t change braking. The advantage of AWD is to help with acceleration on slick roads, but it won’t help you when slowing down.
2WD or 4WD: Which Do You Need?
If you’re still on the fence, here’s a quick guide to help you decide what you need.
Consider buying an AWD or 4WD if you:
- Tow often, or occasionally tow heavy loads
- Enjoy off-road adventuring, camping, hiking, and other outdoor activities
- Live in a rural area with dirt and gravel roads
- Have a job that takes you down dirt and gravel roads
- Live in a mountainous or cold region with more than a week or two of snow and ice
Stick to 2WD, either a FWD or RWD, if you:
- Don’t tow much or only haul light loads
- Live and mostly stay in an urban area
- Value fuel economy as your top priority
- Live in an area with lots of sun and high temperatures such as L.A., Miami, or San Antonio
- Don’t mind swapping to winter tires during colder months to provide improved traction
All-wheel drive and four-wheel drive are useful additions to many vehicles, but they aren’t useful to all drivers. Consider if you need the capability and if you’ll use it. Look at the downsides too. If those don’t scare you off, you may want to check the AWD or 4WD box on the options list.