But I love these mud flaps!!

[i_am_socket]

RE: Corolla dam - yeah, that's in front of the rear wheels; not too bright to hang a mud flap there. It does do something: it does give me a mount point for future wheel-tails/dams

I saw a Prius on the highway the other day with mud flaps and an empty roof rack speeding along with the windows down. Talk about not getting it...

[Xringer]

That Prius was likely doing over 35 MPG (which is my goal)..

When I looked at your Toyota pic, I was thinking that was the left rear wheel.!.

Yeah, that does look like the perfect mount for a nice little air dam..
I'll have to check my wife's Toyota and see if there's any mounts under there.

Well, It's not too hot this morning, maybe I'll see if I can get those mud flaps off the car, without removing the wheels..
Which would be a little too much work for an old geezer in this heat!

[Xringer]

They are laying on the garage floor, next to a pile of rear wheel drive parts.

It's 91 out (real-feel 111) so I took a little test run up I-95 for about 25 miles.
The coolant stayed at 185 for the trip and peaked at 202 while stopped.

I was displaying(X-gauge) my AFE (trip-current-MPG) on the way over to I-95.
The hills, lights and stop-n-go back streets weren't kind.
It started out at <8 MPG, but by the time I got to I-95 it was showing 20 MPG!

(My X-gauge letters 'AFE' stands for Average FE).

Once on I-95, I hit the reset. I must have been going down hill a little,
since the AFE started off in the 40s! So, I waited for a flat spot.
When the real time MPG was about 30, I hit the trip MPG reset again.
Got a good reset that time. The AFE started off at 30 MPG and dropped at the first hill.
But, at the next hill, the drop wasn't quite as much. So, I kept driving.
Slowly, the AFE got up to 33! It would move up and down a little
as I went up and down hills, but it was slooooowly moving up.
At the exit & turn-around, it took a little hit. But once I was on the way back,
it was at 33 pretty fast and slowly getting better! By the time I got back and
took my exit, it was up to 34.6 MPG!

Due to the traffic on I-95 today, I had to drive faster than I wanted to a few times.
But I think my average speed was about the same as the last run up I-95. (52 MPH & 33 MPG).

After deleting the mud flaps, I had expected to see between 0.5 & 1.0 MPG
improvement. So, the first test run seems to confirm there was some
improvement. It's likely that I'll never know exactly how much.

Humm, I wonder what the wind load is on that Ham antenna?

Anyways, my goal of 35 MPG highway seems to be within easy reach.
However, I still have to get another fill up and input my Tank off-set.
So right now, the only thing I really know with a little measure of certainty is,
there seems to have been some improvement..

[i_am_socket]

Some > None :-D Huzzah!

[Xringer]

These mud flaps had to go.. The bottom lookeds like parachutes.


However, when they were gone that seemed to open the wheel well into a large open area inside the rear bumper. Which might cause more drag and might fill up with snow in the winter..

So, I cut the bottom (flap section) off and re-installed the two rear semi-flaps.


Looks pretty sweet now..

Here's a shot from the rear, showing the large cavity that's no longer so badly exposed to the left rear tire.


I'm pretty sure this change will have only a slight effect on the CD, but it is very likely to be helpful when driving in snow.

[Blue07CivicEX]

Wouldn't hurt to cover over that parachute behind the rear wheel either, I have one on my civic as well, seems like it's there for a muffler maybe? Either way it's not helping anything.

[Xringer]

The muffler eats up a lot of the space on the right side, but the left side is wide open.
Just read a little about rear Diffusers and I think you might be right about the big void being a real drag.

I'll make some measurements and check for some good mounting spots.
Maybe I will try to patch up this problem, since it doesn't seem like too much of a job.