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Want some real MPG data on 4.6L V8 and manual 5 spd?

34K views 46 replies 26 participants last post by  DrumBum  
#1 ·
I live in REdding, CA and work in San Jose, CA area. about 250 miles...I drive this each week. Up til last week, I have been driving a 94 Mazda Miata for last 10 years (315,000 miles!). Started out getting 29-ish MPG and slowly dropped over time to about 25MPG. so for last 2+ years been living with 25MPG. I struggled buying the V8 vs V6 Mustang, but appeared I might get 25 under certain conditions. I gambled and took chance on 4.6l, manual, convertable 05 (19K miles on odemeter).

This Monday was my first test. Sunday PM I bought gas in Redding at about $3.46 per gallon (struggled to get tank full, had to baby pump-gas fill kept shutting off-this fill design SUCKS BAD-Ford should be ASHAMED!!!) and drove to my house, then next morning hit freeway (I-5). once I got up to 70MPH, reset MPG, only ONCE during entire trip. THen I changed over to bar graph data mode.

Maintained about 23.5MPG (to my shock), some up and down due to rolling hills for first 30 miles. then leveled out, and about 60 miles out I stopped for coffee, then back on freeway. Stopped once more in Williams, about 100 miles out. then freeway again.

monitoring MPG and bar graph, I noticed once I hit flat ground the MPG started climbing with time. by the time I stopped in Vacaville for gas I had driven EXACTLY 153.2 miles, 6.2 gallons reported as used, 26.0 MPG!!! Amazing! (BTW, I took photos of speedometer at regular intervals for record keeping,noting trip meter, MPG and gallons used-also gas pump I filled up at.)


Actual fill-up was 6.061 gallons (at $3.89 per gallon), so I actually got 25.32MPG (remember, i RESET the MPG after i drove to get gas and hit freeway). (Again, had to fight to fill up tank BAD).


CONDITIONS;

temp 65-75 F
wind = ~0
elevation - 500Ft above sea level
Fuel = Arco, 87 octain, summer blend ethynol.

Observations:

1. any stopping resutls in drop in MPG. So appears simply momentium of getting mass moving is hard on MPG (Duh!)
2. driving at 70 vs 75 mph appears to make big difference, as much as 3 MPG. I will try this next week.
3. watching and adjusting using bar graph indicator helps. (I used it for surface street driving also, helps alot)
4. Keeping RPMs below 2K makes huge difference. SHort shifting!

the balence of trip is traffic driving, some bumper to bumper, also surface streets. Even so, still was 23 by time I hit work, with new tank of gas. SHould not this week, all surface street, about 28 miles from work to apptment I stay in each day, still getting 20MPG.

I still am considering trading this in on V6 auto convertable, if I could get 29mpg, might be worth it...appears to have almost the same HP at similar torque...

I will update this as I get more data.
 
#12 ·
That is advertised MPG, why so surprised?

The fill system is fine, just get yours fixed. It is a problem many newer cars encounter here and there.

Even at 440 crank (estimated with an 18% loss due to 4.10 gears), I still get 23-26 MPG highway (after my latest dyno tune). But just as you described, the minute there is a slight incline, the MPG tanks lol
 
#14 ·
Correct. Ethanol in theory was supposed to be cheap fuel. It is now waaaaaayyyyyy more than regular fuel but it is only cheaper in some places because state and federal subsidy to offset the gaff that has become ethanol. You get a little boost in power but it is absolutely worse MPG.
 
#17 ·
I get about 17 city, 22 highway with 3:73s. I shift typically at 2800. That's also in a 98.
 
#18 ·
Supercommuter said:
I live in REdding, CA and work in San Jose, CA area. about 250 miles...I drive this each week. Up til last week, I have been driving a 94 Mazda Miata for last 10 years (315,000 miles!). Started out getting 29-ish MPG and slowly dropped over time to about 25MPG. so for last 2+ years been living with 25MPG. I struggled buying the V8 vs V6 Mustang, but appeared I might get 25 under certain conditions. I gambled and took chance on 4.6l, manual, convertable 05 (19K miles on odemeter).

This Monday was my first test. Sunday PM I bought gas in Redding at about $3.46 per gallon (struggled to get tank full, had to baby pump-gas fill kept shutting off-this fill design SUCKS BAD-Ford should be ASHAMED!!!) and drove to my house, then next morning hit freeway (I-5). once I got up to 70MPH, reset MPG, only ONCE during entire trip. THen I changed over to bar graph data mode.

Maintained about 23.5MPG (to my shock), some up and down due to rolling hills for first 30 miles. then leveled out, and about 60 miles out I stopped for coffee, then back on freeway. Stopped once more in Williams, about 100 miles out. then freeway again.

monitoring MPG and bar graph, I noticed once I hit flat ground the MPG started climbing with time. by the time I stopped in Vacaville for gas I had driven EXACTLY 153.2 miles, 6.2 gallons reported as used, 26.0 MPG!!! Amazing! (BTW, I took photos of speedometer at regular intervals for record keeping,noting trip meter, MPG and gallons used-also gas pump I filled up at.)

Actual fill-up was 6.061 gallons (at $3.89 per gallon), so I actually got 25.32MPG (remember, i RESET the MPG after i drove to get gas and hit freeway). (Again, had to fight to fill up tank BAD).

CONDITIONS;

temp 65-75 F
wind = ~0
elevation - 500Ft above sea level
Fuel = Arco, 87 octain, summer blend ethynol.

Observations:

1. any stopping resutls in drop in MPG. So appears simply momentium of getting mass moving is hard on MPG (Duh!)
2. driving at 70 vs 75 mph appears to make big difference, as much as 3 MPG. I will try this next week.
3. watching and adjusting using bar graph indicator helps. (I used it for surface street driving also, helps alot)
4. Keeping RPMs below 2K makes huge difference. SHort shifting!

the balence of trip is traffic driving, some bumper to bumper, also surface streets. Even so, still was 23 by time I hit work, with new tank of gas. SHould not this week, all surface street, about 28 miles from work to apptment I stay in each day, still getting 20MPG.

I still am considering trading this in on V6 auto convertable, if I could get 29mpg, might be worth it...appears to have almost the same HP at similar torque...

I will update this as I get more data.
Check out www.ecomodder.com. or its on my Sig, I track fuel their, fully.com, and fueleconomy.gov. Ecomodder may be able to help. There are a lot of great ideas, and like me, a lot of people who just want to fix the stupid mistakes the auto manufacturers made-grilles, under bodies, so on.

Look forward to following this.
 
#19 ·
@DaBlueDude

Yes, my car is bone stock, light metalic blue-looks like chick car. I need to man it up if I keep it.


INSTALLMENT 2: Idling!

Took a phone call, stopped in parking lot to talk. Do this often, in California talking on phone = ticket.

WHile chatting, I left motor running. Call lasted 33 minutes. Car had dropped 1MPG during call, from 20 to 19. Never recovered on that tank.
 
#25 ·
Around town, I average about 21.5 if I drive moderately. If I baby it which I tested this week, I averaged 24. 3.55 gears, airaid cai, and 87 hybrid tune. I really tried the OP's advice on short shifting and keeping rpms below 2k. Plus it also helps with warmer weather coming and the car warming up significantly faster.
 
#29 ·
That's a kool write up.

I run 91 tune and get 16 City and about 22 Hwy my computer says I have 325 miles till empty when I fill up.

Sorry guys, but I've never had a issue filling my Stang up with fuel. She takes it like a cheap whore on nickel night.:D:D:D