Jimny GLX 2022 -Question

Hi guys,
My Jimny's rear wheel well, seem to be incomplete (i.e., the wheel well does not meet the bottom of the rear bumper, and the rear bumper seems to be an air scoop - adding significant resistance on the interstate, or wherever traffic movement is done in the 50-70mph.
-Is it as it should be? (talked to my garage, and they said it was intentional, to enable easy access for debris and mud removal, which seems like an excuse more than the right answer).

-Any help in understanding if this is the way it's designed, and if there are solutions to it - are welcome.

How have you measured the air resistance to know that it is causing the issue you are claiming?

Quit simply, it has to do with common sense, and some aerodynamics.
During forward motion, the air in the wheel wells flows backwards.
Specifically between the tires and wheel well.
Under negligible wind conditions, and inside the range of 50-70 MPh, the flow is in the turbulent regime (not laminar nor chaotic).
Under these conditions any scoop shape, that's opening up to the incoming air will create significant drag and also disrupt the air flow to create chaotic flow, which affects the overall drag of any moving object in a significant way.
The simplest way to get some data in relation to what I described, is reading up on air intake design for the early jets.
-Although the speed range is not the same, the air foil and overall design in of an aircraft is not the same too.
-So, it only demonstrates the drag effect of scoops which intake air, not a linear parallel - but extensively studied.

To illustrate, I attached a photo of the forward facing cavity, of which I'm referring to. This photo was taken front to back direction, obviousle outside the wheel well looking in.

In my opinion, it screams drag.
 

I understand what you are saying, but every item in front of the "bumper Scoop" is impacting the way the air travels over the bodywork.
So without wind tunnel results it's difficult to say what impact the "scoop" design has on overall performance and drag.
IT could be like a deployed parachute, then again it could be almost nothing.
The Jimny itself is a square brick, not one of the better aerodynamic shapes. So overall even if "bumper Scoop" is contributing, which we don't know, the overall brick shape is the big issue. Both frontal area and the air turbulence generated by its "square butt" as the air departs the bodywork, I suspect as turbulent as it can get.
It's not the best vehicle to worry about aerodynamics.  Just enjoy it.

 

My Gen3 looks very similar so I suspect something isn't missing and that is how it is meant to be.

I disagree with the comment about making better access, mine just collects muds on the bottom of that cavity.

Most cars are not very aerodynamic, some better than others, but the Jimny is more like a van than a car, a brick on wheels, so I doubt that this cavity is making any difference to the overall wind resistance of the vehicle.

While I accept the premise of any improvement is better than nothing I wonder that a Jimny is really a suitable candidate for worrying about an odd percent improvement here and there. It might be a useful conversation on an endurance racer or F1 but honestly a Jimny has bigger problems with its aerodynamics.

wrote:

Quit simply, it has to do with common sense, and some aerodynamics.
During forward motion, the air in the wheel wells flows backwards.
Specifically between the tires and wheel well.
Under negligible wind conditions, and inside the range of 50-70 MPh, the flow is in the turbulent regime (not laminar nor chaotic).
Under these conditions any scoop shape, that's opening up to the incoming air will create significant drag and also disrupt the air flow to create chaotic flow, which affects the overall drag of any moving object in a significant way.
The simplest way to get some data in relation to what I described, is reading up on air intake design for the early jets.
-Although the speed range is not the same, the air foil and overall design in of an aircraft is not the same too.
-So, it only demonstrates the drag effect of scoops which intake air, not a linear parallel - but extensively studied.

To illustrate, I attached a photo of the forward facing cavity, of which I'm referring to. This photo was taken front to back direction, obviousle outside the wheel well looking in.

In my opinion, it screams drag.

 

I think they are some HUGE assumptions being made here, and I want to start with this one  ...

During forward motion, the air in the wheel wells flows backwards.

I don't know how familiar you folks are with the so called "classic Mini" (I'm referring to the 1959 Alec Issigonis design here), but, if you're not, it's transverse engined, and unlike most transverse engined vehicles, the radiator is not fitted across the front of the car with an electric fan, it's in the left wheel arch with a conventional belt driven fan - during testing it was discovered that the rotating wheel created a low pressure zone on the outside of the radiator which improved airflow through the radiator so significantly that they were able to reduce the size of the radiator, by, if my memory is correct, close to 40%.

Now I recognize that the rear wheel arch on a Jimny does not air flowing into it through a grill as the front wheel arch on a Mini did, I'm recounting this story simply to demonstrate that air flow in a wheel arch with a rapidly rotating wheel is not linear, not related to the forward motion of the vehicle and definitely not a simple matter of common sense.  The information, by the way, comes from a book called "The Mini Story" published back in 1964.

Absent wind tunnel testing, there is no evidence to suggest that the shape of the rear bumper causes "a significant amount of drag" as you are claiming.

Common sense on my part questions how many of us bought a Jimny expecting to use it for high speed commutes where drag would be a potential issue - before buying the Jimny that we have, I cautioned my wife & daughter that it was not suitable for long road trips and was firmly put in my place with the statement "we have other cars for that".

My gen 3 has no bumper so no drag in theory 
And i can confirm i still only get 150miles per tank