2wd vs 4wd Difference
More than half of the vehicles produced by manufacturers in different parts of the world are 2 wheel drive vehicles. They are the most preferred mainly because they are cheaper at the point of purchase and cheaper to maintain.
Some drivers say the smaller 2 wheel drives have better handling and are easier to drive. This is attributed to their relatively low weight and small size in comparison to larger, heavier 4 wheel drive vehicles.
What are some disadvantages of 2wd systems?
When it comes to wheel-drive descriptions, it is best to first understand what the digits mean.
Four wheel drive vehicles are described as 4×4 and two-wheel drive vehicles are described as 4x2s. The first digit refers to the number of wheels and the second refers to the number of driven wheels.
A 4×4 vehicle has four wheels, all of which are powered in order to make the vehicle move. A 4×2 has four wheels but the engine only powers two sets of wheels.
There are two types of 2wd vehicles: front wheel drive (FWD) and rear-wheel drive (RWD). In FWDs it is the 2 front wheels which are powered and the rear two spin along.
In RWDs it is the rear two wheels that are powered and the front two are pushed along. Most manufacturers prefer to produce FWDs because they are closer to the engine. It is easier to transfer power over a short distance.
2wd is best for everyday road driving on tarmac and paved roads. 4wd is best for off-road driving on rocky, rugged terrain, mud or snow because it provides twice the power a 2wd system does.
Most 4wd vehicles have the 2wd mode as the default driving mode and it is up to the driver to switch to 4wd mode when need arises.
The process of engaging 4wd mode varies depending on the individual vehicle. Some have a dial, for others it is a button and in others it requires a gear change.
The Pros of 2 Wheel Drive
Weight
The most substantial advantages of 2wd vehicles over 4wd ones are in relation to weight. Vehicles with 4wd drivetrains require more mechanical components to deliver the extra torque. These parts are also larger in size. All these contribute to significant additional weight.
Fuel Economy
2wd vehicles give much better fuel economy compared to 4wd ones. This is mainly because the engine in 4wd vehicles has to deliver power to all four wheels while the engine in 2wd vehicles only needs to deliver power to 2 wheels.
The additional power requires more fuel. 4wd vehicles are much heavier than 2wd vehicles and the additional weight also requires extra fuel to support.
Better Handling
2wd vehicles have better handling. They are generally easier to drive because of less weight.
Initial cost
It will cost you less to buy a new or used 2wd vehicle compared to a 4wd.Typical price differences between the two range between $1,000 and $3,000.
Cons of 2 wheel drive
Off-roading
The main weakness of 2wd vehicles will not be felt by drivers living in warm areas where there is no snow or ice. If you do live in an area which encounters snow, your 2wd may get stuck in the snow. If you like off-road driving, a 2wd will not be able to handle rough trails.
Nose-heavy
In front-wheel drive vehicles, the bulk of the vehicle’s overall weight is in the front. This makes it nose-heavy. This imbalanced distribution of weight makes them difficult to handle in high speed and when the vehicle is carrying heavy loads.
Do I Need A 4wd or 2wd Truck?
It is a common misconception that all pick-up trucks have 4wd systems. Although trucks are generally associated with rough roads and carrying heavy weights, a good number are 2 wheelers.
If you have shopped around for a pick-up truck you have probably realized that mid-sized trucks are generally 2 wheel drives, in the half ton class you will have options between 2wds and 4wds. For heavy duty trucks, the options are more or less limited to 4wd systems.
When deciding whether to buy a 2wd or 4wd truck, here are some of considerations to keep in mind.
Use of the truck. What do you intend to use the truck for? If you expect to use the truck to carry heavy loads on a regular basis then you are better off with a 4wd truck.
Expected Terrain. What kind of roads do you expect to be driving on? If you like off-roading and expect to be doing a lot of off-road driving, a 4wd is a good option. If you are not the off-roading type and you live in a city with well tarmacked roads, a 2wd will serve you fine.
Budget. 4wd vehicles are generally more expensive than 2wd vehicles. What are you able and willing to spend?
How to Add Traction to a 2wd Truck
After taking all these factors into consideration, you settles on a 2wd truck. You never have to carry very heavy loads and rarely go off-roading. However, once in a long while you need to drive on rough roads or in the snow.
The weight of the front end of the vehicle is significantly higher than the weight of the back end so you may lose traction on unstable surface roads. Here are some tips on how to improve traction on you 2wd truck.
Add weight to the bed of the truck. Some people actually put sandbags in the back of the truck directly above the rear axle. If you can’t find sandbags, you could also use a truck bed cover or a camper shell. This will definitely improve traction but the increased weight will increase fuel consumption.
Make sure your tires are always in good condition. Worn out tires have minimal tread and are more likely to lose traction than new tires.
If you have a 2wd truck that is regularly exposed to conditions ideal for a 4wd, make sure you never let your tires get worn out. Replace them when they are about halfway through their recommended mileage lifetime.
What is Automatic 4wd?
4wd (four wheel drive) or 4×4 generally means that the vehicle’s drive train system is capable of powering all four wheels but the four are not necessarily all powered at the same time. Automatic 4wd (auto 4wd) is one of 3 types of 4wd systems. The other two are full-time 4wd and part- time 4wd.
Full-time 4wd is also referred to as permanent 4wd. In this system, the drivetrain powers all four wheels all the time. The driver does not have an option to switch from one system to another. The vehicle is permanently in 4wd mode. This ensures maximum traction at all times whether you are driving on dry or slippery roads.
Part-time 4wd. Vehicles with this kind of system are capable of operating on either 2wd more or 4wd mode. Unlike in full-time 4wd vehicles, the default driving mode in part-time 4wd vehicles is 2wd.
The driver makes the decision to engage 4wd mode when he encounters rough, rugged terrain. The 4 wheel powering mode is engaged by pressing a button, pulling a lever or turning a dial
Auto 4wd. In this system the vehicle operated under 2wd mode. Either the front 2 or rear 2 wheels are powered. When the vehicle is driven onto rough or slippery roads.
The system judges that 4wd powering in needed and automatically activates it. It immediately routes power to all four wheels and varies ratios between front and rear axles as required. A slipping wheel is sufficient to activate 4wd mode.
The main difference between part-time 4wd and automatic 4wd therefore, is in the discretion to switch from one mode to another.
In pat-time 4wd vehicles, discretion is left to the driver who has to engage 4wd mode and in auto 4wd mode, discretion is left to the vehicle’s system. The switch is done automatically without any intervention from the driver.
Does Auto 4wd Use More Gas Than 2wd?
What causes differences in fuel consumption between 2wd and 4wd vehicles?
2 wheel vs. 4 wheel powering. 2 wheel drive vehicles generally give better gas mileage than four-wheel drive vehicles. The first reason is because of the amount of torque required to power all four wheels in 4wd vehicles compared to 2wd vehicles. More power requirement translates to higher fuel consumption.
With this in mind you will probably wonder if 4wd vehicles will then consume the same amount of fuel as 2wd vehicles as long as the 4wd mode is not engaged. Does Auto 4wd use more gas than 2wd? The answer is still an emphatic yes.
Overall weight of 4wd vehicles. 4wd systems can add hundreds of pounds to the overall weight of a vehicle. This means the engine requires more power to keep the entire vehicle in motion as compared to a lighter 2wd vehicle.
More power means increased fuel consumption. Therefore, your 4wd will consume more than your 2wd whether you engage 4wd mode or not.
Maintenance Costs for 4wd Vehicles
Fuel costs aside, it is important to keep in mind that it will cost you a lot more to maintain a 4wd vehicle than a 2wd one. When you need to replace parts such as brakes and tires, you will find that the cost of parts for these type of vehicles is higher than for 2wds.
When you take your car to the shop for routine maintenance such as servicing, the numbers build up because of seemingly insignificant details like the amount of oil required. The extra few liters of oil are an expense which will be included in the overall cost of servicing.
These vehicles have more parts so servicing will take longer. Don’t forget that time lost very often means money lost.
There may be lots of professional mechanics out there but there are fewer professionals who know their way around the mechanics of four wheel vehicles compared to those available for the more common two-wheelers.
Does AWD Use More Gas?
Fuel consumption is one of the main considerations to be made when deciding which car to buy. You may be able to gather enough money to buy that sleek 4 by 4 but the constant cost of fuel may be more than you can afford.
There is no objection on the claim that 2wd vehicles are more fuel efficient than 4wd and AWD ones. Debate arises when it comes to fuel efficiency comparisons between 4wds and AWDs. Does AWD Use More Gas and is the difference significant?
Why Is AWD Less Fuel Efficient?
When it comes to fuel efficiency, there is a notable gas mileage difference between AWD and 4wd vehicles and a big difference compared to 2wd vehicles. This is why.
Power Distribution
The AWD system has to distribute power to 4 wheels and not 2 wheels as is the case with 2wd vehicles. The extra power inevitably takes more fuel. This is why a 2wd vehicle requires less gas to cover an equal distance compared an AWD vehicle.
More Mechanical Components
In order to achieve sufficient torque for all 4 wheels, the engine of an AWD vehicle has to get twice as many parts moving, compared to a 2wd vehicle.
All the extra hardware translates to additional weight and the load has to be carried along. The additional power required by the engine to bear the load means increased fuel consumption.
Option to Engage and Disengage 4wd Mode
Making a comparison between 4wd and AWD, the fact that you have the option to disengage 4wd mode and drive on 2wd mode means you can save significant amounts of fuel as long as you are on 2wd mode.
Many 4wd vehicle owners spend 70% – 80% of drive time on smooth paved or tarmacked roads and only about 30% on rough terrain. This means you have the opportunity to remain on the cheaper 2wd mode and consume much less.
How to Reduce Fuel Consumption of AWD
Several years ago, AWD systems were restricted to jeeps and trucks. Today the system is fitted to 1 in every 3 new vehicles sold in the United States.
As vehicle manufacturers fit this system into more and more vehicles, they cannot be blind to the issue of poor fuel efficiency. They have to come up with strategies to reduce fuel consumption.
Subaru and Audi are 2 top companies famed for all-wheel drive vehicles. One method they have used in an attempt to reduce fuel consumption is a drive system where only the 2 front wheels are powered.
When the road gets rough, sensors detect a reduction or loss of traction. This essentially means that there is need for additional powering. At this point a second set of driven wheels kicks in so all four wheels are powered at the time of need.
A system used in the 2014 Jeep Cherokee goes a step further. It has a clutch placed between the transmission and rear-drive components so that none of these components are turned by the engine until required. This reduces gas mileage by about 3 miles per gallon.
Other Drawbacks of AWD Vehicles
Fuel efficiency aside, there are several other challenges faced by owners of AWD vehicles.
Initial cost of purchase. AWD vehicles are more expensive than 2wd ones. Whether you are buying it brand new or used, it will cost you more than a 2wd.
Breaking distance. The increased overall weight of AWD vehicles helps to add traction which is good for off road driving. On the other hand, it also increases braking distance which means it requires more distance to come to a complete halt compared to a 2wd vehicle.
Cost of spare parts. If you bought a used AWD vehicle, it may not be long before you have to replace something. Parts specifically for these types of vehicles are more expensive than those used on smaller vehicles.
Let’s not forget that the AWD system has more mechanical components. All these will require to be repaired or replaced at some point.
Complex System. AWD vehicles have more complex transmission systems compared to 2wd vehicles. These systems require more advanced personnel to carry out repairs.
FAQ
Can You Change A 2WD To 4WD?
Yes, you can. Firstly, for this to work you will need to change the 2WD output shaft to the one for 4WD.
The process is quite labor intensive as you will need to dismantle the transmission assembly. To save on costs you can go to a salvage yard and get old front diff, CV shafts and suspension.
Is It Safer Driving In A 4WD Than In 2WD?
When it comes to car safety there is no evidence to show that driving a 4WD reduces the chances of getting into accidents as compared to the 2WD.
This myth has probably been propagated due to the large size of 4WD SUVs but car safety will largely be dependent on driver experience.
Conclusion
2wd vehicles are no-doubt the more popular system no matter which part of the world you are in. They are cheaper to buy, easier to handle and cheaper to maintain.
Despite these strengths, there are some disadvantages of 2wd systems. These vehicles are not the best for off-road driving and easily get stuck in mud or snow.
If you have to drive on rough, rocky trails you may have to incur the cost of a lot of repairs as a result of damaged parts.
When it comes to trucks, it is time to dispel the misconception that all pickup trucks are 4wds. Some trucks have 2wd systems and serve just fine provided they are not used for off-roading or to carry very heavy loads.
