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Why is Jeep Wrangler Gas Mileage so Bad?

Jeep is an incredible vehicle due to its ability to use in a variety of ways as a daily driver or as an extreme off roader

When it comes to off roading, normally we can’t expect a good fuel efficiency in most of the vehicles. 

But to use as a daily driver we have to consider the fuel efficiency also. 


Actually why is the jeep wrangler gas mileage so bad?

There are many reasons for the bad gas mileage of a jeep wrangler. 

Common reasons will be significantly heavy weight (range from 3,970lbs to 4,439lbs) and lack of aerodynamic body shape. 

Apart from those two facts, improper driving habits, different modifications and mechanical defects like oxygen sensor failures affect highly on the bad gas mileage of a wrangler.

Let’s look at how the above factors affect the gas mileage of a jeep adversely, how we can improve the gas mileage of a jeep and some other jeep MPG (miles per gallon) related queries through this guide.

How bad is gas mileage of Jeep Wrangler?

There are stock jeep wranglers that only run 13 miles per gallon as well as new jeep wrangler eco diesel models that runs 29 miles per gallon. 

That means wranglers fuel efficiency lies in a vast range, due to a variety of reasons. 

How the weight of a wrangler affects gas mileage?

Older versions of the jeep wranglers manufactured with heavily weighted aluminum material body design. 

Frame is fully steel. With those heavy strong designs this can stand against high off roading abuses for years. But with the heavy weight, MPG reduces.

As a solution for that new wrangler jl are made with strong but somewhat lighter material. That may also be a reason for reporting such a high gas mileage in the new eco diesel wrangler model.

Apart from the weight of the jeep, users also put lots of extra weight in the jeep when using it due to it’s larger cargo space. Those weights also result in reducing MPG.

Wheel size.

Wheel size affects the MPG of wrangler in two ways. One is weight of the tires and other one is extra frictional force effect on the wheels due to larger off road ready wheels.

If you are running with stock street tires the second fact may not affect much, because there footprint is not wide as off roading tires as well as there tread patterns also not try to hug the road like off road tires.

The weight of the wheel is also highly affected for the MPG because, engines have to roll them on the ground.

So an increase of only one pound of wheel weight also highly affects the MPG.

How aerodynamics affects the gas mileage of wrangler?

Simply here aerodynamics means how air flows around and inside the jeep when it’s moving.

When the speed of the jeep increases the effect of the air on handling, gas mileage as well as on the top speed increases.

Normally road vehicles make best possible shapes to reduce the adverse effect of aerodynamics on the vehicle. 

But jeeps just have a boxed shape, a large flat, vertical windshield and a flat vertical face with grill slots.

On both sides large fenders have been placed. This type of body shape is better for off roading purposes. 

But when it comes to highway driving, things get worse.

Huge wind resistance at high speeds trying to slow down the vehicle while the engine tries to overcome that resistance and keep the speed constant.

This highly increases the gas consumption of a wrangler.

Installing aftermarket parts

With installing heavy metal front bumpers, winch, huge tire carriers, roof racks, skid plates, wranglers weight highly increases.

With those extra weights MPG reduces in no time.

Next hidden factor is that due to some of these extra modifications, wind resistance increases more. 

Roof racks and LED light bars above the windshields as well as some aftermarket front bumpers also reduce the aerodynamic shape more and more.

Other possible factors for bad gas mileage of wrangler.

If you are owning a jeep right now and you are disappointed with the bad gas mileage of your jeep, below are a couple of things you have to be aware about.

Improper alignment of wheels

This may seem simple but jeeps are highly prone to alignment changes specially with off roading activities. 

Change of wheel alignment reduces the freedom of the wheels and engines have to exert extra force on those kinds of wheels than on properly aligned wheels.

So it can affect the reduction of gas mileage of your wrangler.

You can read ” wheel alignment after off roading ” guide to know more information, by clicking here.

Defects of oxygen sensors

This is very common cause reducing gas mileage of wranglers.

One oxygen sensor is placed in the engine’s exhaust manifold area to detect the concentration of oxygen in exhausting gas. 

This sensor compares the oxygen concentrations among exhaust gas and the outside atmospheric air and sends those details to the computer system of the engine. 

That system regulates the amount of fuel injected to the air-fuel mixture to the combustion chambers

But if the oxygen sensor failure happens, the computer system starts to work in an open loop method.   

That means more and more fuel will be injected to the mixture to enrich the mixture.

It causes a decrease in the MPG and many other complications like stalling of the engine and so on.

Fuel injector malfunctioning

Fuel injectors are responsible for injecting fuel to the Air – Fuel mixture. With the time fuel injectors can block with dirt and cause failures of proper fuel injection.

That also results in the reduction of gas mileage.

Apart from the above, fuel pump and fuel filter failures, spark plug malfunctioning, binding of brakes can also result to a bad gas mileage of jeep wrangler.

How can I get better gas mileage in my Jeep Wrangler?

Driving pattern plays a huge role in gas mileage. Don’t mash the gas pedal to the floor every time.

Go easy with the gas pedal to accelerate slowly and keep your speed under limits.

To get a better gas mileage from your jeep you should try to reduce the overall weight of the jeep. 

Carrying only the essential things inside the jeep.

Avoiding heavy steel bumpers, keeping plastic bumpers and flares reduce the weight as well as support the aerodynamics.

Avoiding larger tires, and keeping tire pressures at optimal values.

If you want to modify your jeep try to do them concerning the aerodynamics as well as overall weight of the jeep. 

Do periodic check ups of oxygen sensors,spark plugs, fuel injectors, fuel pumps and filters and clean or replace them as necessary.

If you are willing to buy a jeep and are highly concerned about MPG, try to choose a 4 cylinder manual jeep. Power will be a bit lower but MPG is high on those jeeps.

Using a 4WD system only when necessary. Using 4WD prolonged periods of time reduces the MPG.

Wrapping up

With this guide I tried to show you some important facts regarding how gas mileage changes in a jeep wrangler.    

If you are willing to buy a jeep and still worrying about the bad gas mileage, I think now you get an idea about how the gas mileage has been reduced in most of the jeeps. 

If you want you can improve the gas mileage of a jeep into a sufficient amount without breaking the bank.

If you think this guide may be helpful for someone else, you can share this with them. You just have to hit a share button below.

Have fun and safe jeeping!!    

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