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Discussion Starter #1 (Edited)
Yep - that's my goal this week.

I'm taking my eco-modded 2.3 and going on a road trip.
Cajon Summit, CA to Provo, UT on one tank of regular unleaded.

The car?
My 1992 2.3/A4LD ragtop

The mods?
Junkyard Underdrive Pulleys
(crank, water pump, and alternator pulleys)
3" Aluminum mandrel bent intake tube
Accel drop in filter with gutted airbox
NGK fine wire platinum plugs
144cc Denso fuel injectors
pre cat removed and oem 5.0 muffler installed
Gutted trunk
S-10 front air dam
45 psi in stock 195-75-14 tires

The driving style?
freeway cruise at 55mph
neutral coastdown on hills and signals
engine shutoff at red traffic lights

I have seen 40-41mpg on similar controlled driving adventures locally so if all goes well, I'll get 600 miles worth of travel on a single fillup.

I'm leaving thursday early a.m. and hope to be in Provo later that day.

Wish me luck!
 

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1. I think its illegal to turn your car off at red lights. Also, I think it uses more gas to start rather then waiting 45 seconds or so.

2. 55? You drive slow! hahaha

But with all seriousness, good luck to ya! Gas is a bitch so its good to see its not hurting the 4 banger crowd too much
 

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Lol there is no way that it takes more gas to start than to run it for 45 seconds. just sayin
 

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Good luck Rob!!! I'm slowly working on getting my car in driving shape and going to do some of the stuff to my car as you did to get great mileage. As of now, my car only gets 17 mpg. Its parked until I get the cosmetic stuff fixed and then time to tune up the car. I think you can hit 600!!
 

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Did you make it there? Results?
 

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Discussion Starter #8 (Edited)
Mission completed.

I'm up in Provo right now, and I almost made my goal. :(

I made it as far as 20 miles outside Provo before I absolutely had to buy gas.

The results:
561 miles / 15.24 gallon used = 36.81 mpg

I figure the lower than expected fuel economy occurred because of 3 variables...

1. I had a tire blow out the day before the trip, so I had to change out my rear tires (195/75-14) to a pair of larger 215/70-14 tires. I believe this added weight and more rolling resistance than what i had.

2. I added an S-10 air dam, and it might be overkill. The airdam extends to only 4.25" above the road so I am probably increasing my frontal area since the dam hangs lower than the other chassis components below the car.

3. Mountainous trip. I started the trip at 4300 ft elevation and ended it around 4400 ft, but the elevation changes went from near sea level of the mojave desert to many utah summit passes with elevations as high as 6900 ft.
 

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Discussion Starter #9 (Edited)
true you use less gas by turning the car off and restarting. But it puts more stress on the engine
I think one beats up their ignition switch and starter more than the potential wear of oil starvation during startup. Oil is most likely coating all the parts just fine, since the shutdown was a short duration.
 

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Discussion Starter #10
1. I think its illegal to turn your car off at red lights. Also, I think it uses more gas to start rather then waiting 45 seconds or so.

2. 55? You drive slow! hahaha

But with all seriousness, good luck to ya! Gas is a bitch so its good to see its not hurting the 4 banger crowd too much
I can always tell the officer the car stalled if i was stopped for such a despicable traffic crime as that.

As for the 55mph... mpg improves a great deal when you keep the engine rpms of the 2.3 under 2300 rpm, and the non aerodynamic mustang body under 60mph for reduced wind resistance. 55mph in OD lockup works out to just over 2000 rpm.
 

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Discussion Starter #11
OK, I'm back home again... the return trip was remarkable similar in fuel consumption. The last fillup was 15.411 gallons over a 561 mile distance = 36.40 mpg.

I got a few check engine light illuminations while climbing long grades so i'll need to check out what that is about, otherwise the car handled the trek beautifully.

I think I'll reward it with a thorough wash and wax job, as well as some new aero mods like a enclosed belly pan and a grill block. :)
 

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Putting the car into neutral doesn't help the mpg any. I used to think this too.


Do some research on it and you'll see. I made a thread, but it was a while ago.
 

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Discussion Starter #13
Putting the car into neutral doesn't help the mpg any. I used to think this too.

Do some research on it and you'll see. I made a thread, but it was a while ago.
if you're referring to while sitting at a light in drive, shifting into neutral can be beneficial instead of leaving it in drive.

i've heard this argument before, and i'm on the side that believes letting a car idle at a lower rpm with no load is more fuel efficient than one maintaining some sort of load by using the brakes to fight the forward momentum of the car while being stopped in drive. it's not uncommon for a typical 4 cyl car to burn 1 gal in 100 minutes of idling in drive. Idling in neutral will cut that figure in half. Not a lot when translated into the real world, but it is something that will make a small difference.

in addition, as a car is sitting in drive, the transmission fluid is being heated up more than if it was in neutral just by the viscous slipping of the torque convertor.

as for shifting in neutral for coastdowns, the car will freewheel down a hill much better in neutral than if it were in drive - that difference can even be felt.

so from a hypermiler perspective, shifts to the "N" during hilly coastdowns and stints at the traffic light make sense.
 

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Putting the car into neutral doesn't help the mpg any. I used to think this too.


Do some research on it and you'll see. I made a thread, but it was a while ago.
When you shift into drive there is a load put on the car, as seen by the car rolling on a flat surface without the brakes. This load also lowers the idle, to fix this the IAC lets more air into the engine (thus burning more fuel) to maintain the same RPM.
 

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Yeah I used to think that was true also, but it really isn't.

Do a bit a research and you'll see.
 

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Discussion Starter #16
here is a measured stop light fuel consumption test that was done on a 2005 chevy malibu:

Idle, in gear, AC on - 0.51 gph (gallons per hour)
Idle, in gear, AC off - 0.43 gph
Idle, in neutral, AC on - 0.41 gph
Idle, in neutral, AC off - 0.29 gph

there is - without a doubt - less fuel being used.

as for decelleration coasting... assuming you do not want to coast farther and are just interested in coming to a stop, then many ecu's are equipped to read the vss, tach, and tps, and from that information shut off the fuel completely, warranting your claim that one uses more fuel if putting into neutral.

BUT - if you plan on coasting a distance longer than the engine braking will allow, like down a long grade with the full intention of never braking but rather putting the car back in gear to accelerate again once the speed drops to an unacceptable level, then neutral coasting is the preferred and more frugal method.
 

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Yeah I used to think that was true also, but it really isn't.

Do a bit a research and you'll see.
To be frank, there is no research needed to be done, its common sense. More load = more HP needed, and more HP = more fuel consumption. And As Rob said, while under DECEL the ECU will shut down fuel completely for a few seconds, but once the engine is back under power switching it to neutral is the better idea. And a long down hill neutral coast will save gas because you travel longer distance with no load (usually gaining speed) and do not have to speed back up for the wasted energy lost by engine braking. the more energy you use and dont get rid of from hills the better your fuel economy.
 

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with that said there is a right and wrong way to go about it.
 

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The mods?
Junkyard Underdrive Pulleys
(crank, water pump, and alternator pulleys)
3" Aluminum mandrel bent intake tube
Accel drop in filter with gutted airbox
NGK fine wire platinum plugs
144cc Denso fuel injectors
pre cat removed and oem 5.0 muffler installed
Gutted trunk
S-10 front air dam
45 psi in stock 195-75-14 tires
Questions/Comments on certain mods
1. Is the intake a CAI type setup or stock?
2. Most cars like either copper or Iridium Plugs, most don't like platinum but, then again I don't know 2.3s, feel free to correct me.
3. You should do a custom header-back exhaust with a Spun high flow cat and straight through muffler instead, it'll give you some more power and MPG.
4. I don't know what rims you are using but, you could get some knock-off lightweight rims for cheap with the low-resistance tires they make for hybrids now.
5. You could try and modify an aluminum driveshaft to work for your car to decrease rotational weight.
 
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