Shooting for 30 mpg with my '92 Mark VII.
 

<---My fuel log indicates the low end of my average MPG when driving to and from work. The best I've seen for a tank was 17.7 mpg, according to my tripminder and miles driven/gallons used. I'm hoping I'll be able to raise my tank average to 30 mpg or more. I'm going to attack my mpg goal from multiple angles.

First and foremost the car needs a transmission since overdrive slips,reverse and the other forward gears are fine, though. The t/v cable popped loose on the previous owner and o.d. was toast before he could get it to a shop. So for now I'm driving with a 1:1 trans gear @ 60% lockup (according to the web). A new trans would be .67:1 o.d. with 100% mechanical lockup. While I'm saving up for a transmission I plan to make a few small, cheap improvements.

There are two routes I can take to work; one that is about 8 miles long and is 50% highway (55 mph limit), and one that is 13 miles long and is about 70% highway (70 mph limit).

My car is basically a long wheelbase, heavy Fox Mustang with an air suspension that uses longer A-arms and longer rear control arms.

From what I've been able to find, the stock AFR for a '92 5.0 Fox falls between 11.8:1 and 12.2:1. Lots of room for improvement there.

My car weighs 3,800 lbs, lots of room for improvement there too.

My car's Cd is .38. I think I may be able to reduce that a bit.

Here's the plan:

Lower the Cd without losing the original character of the car (no boat tail), reduce the curb weight, reduce parasitic drag on the engine, and increase the efficiency of the engine.

Aero:
Remove side mirrors (if legal) and install interior mirrors.
Install a grill block and possibly hood vents
Install an air dam
Possibly install rear skirts, not sold on this idea though.
May install a small spoiler, if needed

Parasitic drag:
Remove smog pump and hoses
Underdrive pulleys
Junkyard electric fan
A/C delete? (not sure on this one)
Thinnest possible synthetic fluids

Engine Efficiency (Mechanical):
Transmission (of course)
1996-2000 5.0 Explorer cam
1998-2000 5.0 Explorer intake with injectors
Roller rocker arms (still debating 1.7:1 vs 1.6:1)
Adjustable fuel pressure regulator (try to tune for 14:1 AFR)
larger, lower restriction exhaust
Narrower L.R.R. tires.

Weight Reduction:
The smog and A/C deletes will net a pretty big reduction
Mustang manual front seats (potential 60 lb loss here)


The overall goal is to have my cake and eat it too. :)
Progress will be slow :turtle:

A/C won't reduce much paracitic drag when not running. It will drop about 25lbs or more from the front end though. Maybe look into a manual steering box too if you don't do a lot of 3pt turns and parallel parking. Air dam and E-fan will help a bunch and should be some of the easier mods to do especially if the car shares more than just suspension with the Fox cars.

What are you looking for out of this car, that the Impreza doesn't cut it at?

The Impreza is the winter beater, this car is the nice 3 season cruiser.

@Spacemanspi: I had considered picking up a manual rack or de-power the o.e. rack but, even after the weight reduction it will still be a 3,600 or 3,700 lb car.

Also it goes back to the character of the car; if it were a Fox Mustang I'd have no troule slapping a manual rack on it and manual brakes for that matter. That's one of the niceties I'll wind up keeping on this car.

My fox weights just under 3k lbs with the spare tire, back seat and rear carpet removed (all back in now) and it's still almost impossible to steer without the p/s pump.

Lotta weight over the nose on these Foxes! :)

I just saw a MkVII on the road today, which is pretty rare around suburban Detroit these days! Good luck on your mods and F.E. progress.

A 'less restrictive' exhaust will not help mpg. The whole idea is to run at low rpm. Not conducive for larger exhaust. Also a less restrictive system would only show a small benefit at wot wide open throttle. How often are you there??????
I had the exact same car 15 yrs ago!
Loved the ride! I did get 28mpg on a 1700 mile trip to Dallas from Sacramento. The trick was to coast engine on down hills and drive 64mph. I did not do any mods.

I would never delete a/c. It's a luxury car. Lose the spare tire.
Also consider changing the rear axle ratio. I bet the lcs (basicly the hotrod edition had a different ratio than the base model.
Or go with a taller tire. The trick is to lower the rpm at cruise.