I really noticed it the first time I washed my JK, I was used to my sponge getting hung up and snagged on my TJ constantly, no such issues on the JK.

I'm not a rocket scientist anymore, but here is what I came up with.

.4847562923194453684098995582736103948675632212100 980562190/.994

This is all fine and dandy, but the aerodynamic problem are thethings that make a JK a
Jeep: flat grill, near vertical winshield, height, bir tires
and mirrors, fenders, etc not to mention frontal area. And then we add mods to make it even less streamline.

I love my JK but like Harleys and bulldozers whic I also admire, aerodynamic effiency is not one of its
virtues. :naw:

Park yours next to a TJ and look at the difference. They made it as aerodynamic as they could with it still looking like a Jeep.

I owned a TJ so I get your point, but let's not confuse fashion (updated styling) with physics. Either way, IMO Jeep did a great job on everything but choice of engine.

It's all good!

I'd rather have my 3.8l than a 4.0l. At least I have power in upper RPM range and get a lot better gas mileage than my 4.0l did.

No argument on the highway in spite of the JKs heavier weight, but the 4.0L was pretty torquey in the low range.

I can't really say I miss the 4.0L, I just have fond memories. It was also easier to change the plugs on the 4.0L. :thumbsup:

OK, I did your research. Not really but after seeing your question I had to find it.
No one seemed to have the info posted. I finally found it on a South African car site called CARtoday. Be patient its a PDF and takes a minute to load. It is a review of the 4 Door CRD.

Back to the Cd, they list it as being better than the TJ at - - - .495 which, if my math is correct, (never is) comes out to just slightly WORSE than a barn door.

OK, for fun here are some things to compare it to.


Type of Object Drag Coefficient - cd -

Old Car like a T-ford 0.7 - 0.9
Common Car like Open Vectra (class C) 0.29
Passenger Train 1.8
Bike Upright Commuter 1.1
Bike racing 0.88
Tractor Trailed Truck 0.96
Dolphin 0.0036 wetted area
Bird 0.4
Solid Hemisphere 0.42
Solid Hemisphere flow normal to flat side 1.17
Thin Disk 1.1
Cube 0.8
Streamline body 0.04
Squared flat plate at 90 deg 1.17
Long flat plate at 90 deg 1.98
Hollow semi-sphere opposite stream 1.42
Hollow semi-sphere facing stream 0.38
Hollow semi-cylinder opposite stream 1.20
Wires and cables 1.0 - 1.3
Laminar flat plate 0.001
Turbulent flat plate 0.005
Subsonic Transport Aircraft 0.012
Supersonic Fighter 0.016
Person (upright position) 1.0 - 1.3
Ski jumper 1.2 - 1.3


chart copied from http://www.engineeringtoolbox.com/dr...ent-d_627.html

All right, broke out the full sized wind tunnel and did the math.

It's 9
. . . or 90

. . . carry the 1 . . . where'd that decimal go?

Yep 9.



Who am I kidding? I have a biology degree. And my jeep is 9000 miles away.

The only thing that really sucked on the 4.0l was accessing anything on the front of the engine like the water pump.