Update ...

Filled up today ... 416.7 miles / 13.304 gal = 31.32 MPG.

At the time of fill up, computer was showing "47-MI to E" and "29.7 AVE MPG".
Total miles on car to date is 6478.6.

Here is a summary of my commute MPG to date:
WEEK 1: 28.81 MPG
WEEK 2: 29.10
WEEK 3: 29.46
WEEK 4: 30.89
WEEK 5: 30.99
WEEK 6: 30.53
WEEK 7: 31.47
WEEK 8: 31.00
WEEK 9: 31.67
new since last post:
WEEK 10: 29.90 (442.4 miles, prior weekend + commute)
WEEK 11: 30.80
WEEK 12: 31.11
WEEK 13: 31.32

I think the MPG has finally stopped improving, and the switch to Mobil 1 at 5k miles appears to have not made any difference.

Since week 9 (31.67 MPG - best), every commute week has had it's issues ... between weather, abnormal traffic jams, or both ... so with perfect traffic & weather I think it is still possible to break 32 MPG.

If I was to drive the speed limit instead of 10+ over (ain't gonna happen), I'm sure 32+ could be the norm.

O/A ave. MPG since new is 29.20 ... but O/A ave. since I 1st broke 30 MPG is 30.47 MPG (still improving compared to #'s at WEEK 10 in post #55).

Doug

 

Okay, if I may make a suggestion...

You mentioned earlier that you are running ethanol-free premium (91 octane) gas in your V6. The V6 doesn't gain anything by running higher octane like the 5.0 does although it does gain from the lack of ethanol. In fact, if you could find regular ethanol-free gas, you would probably get better gas mileage than with premium. Flame propagation with higher octane is slower and adversely affects mileage in cars that don't require it for knock prevention.

Assuming an average of 20 cents more per gallon for premium over regular, you have spent $1295.72 more than necessary for fuel over your 6478.6 miles. Even if running regular gas didn't help your mileage at all, that's an additional 462.8 miles (at $2.80 per gallon) you could have driven for the same cost.

Now, if you're just trying to see how big an MPG number you can achieve, that may not mean much. But if you're trying to get the most from your fuel dollar, that's a significant difference. Even if you allow for the 4-5% loss of fuel economy using E10, that's still well over $400 savings.

Maybe you could try it for a tankful or two and see how much of a difference it makes.

 

^^^ I think he explained earlier in the thread that the 91 is the only ethanol-free gas he can find within a reasonable driving distance

 

I included that...

$439 plus change to be exact.

 

I've only burned 222 gallons of gas since I 1st started driving this car. At $0.20 a gallon, I've only wasted $45 on buying premium. Don't know where you came up with your numbers, but driving 10~15 miles to get ethanol free 87 would be more wasteful.

I also want to support the ONLY ethanol free station in my town as many of us need it for our older cars.

Doug

 

Sorry, my bad. I just multiplied your total miles by 20 cents rather than using your total gallons.

Still... that's $45 you didn't have to spend. That's at least another tank of gas. And trying to preserve the non-ethanol gas supply by buying at that store is admirable but probably futile. More and more states are mandating E10 at all street pumps (Florida did that last year). The only place we can get plain gas in Florida is at marinas or private airports.

 

You could nitro fill your tires to try for the 32 mark.

 

A lot of message board users keep stating that the 3.7L will not adapt to better than 87 octane, but I have not read one article that quotes a Ford official stating this.

However, in the June 2010 Muscle Mustangs & Fast Fords 3.7L article it is stated that it WILL adapt to better fuel ...

The powertrain ECU has been upgraded with a very aggressive deceleration cylinder shutoff for fuel economy, coupled with very rapid tip-in for street performance. On the flip side, the ECU has been reprogrammed with adaptive-knock spark control. If the two knock sensors embedded in the cylinder block don't hear knocking, the ECU will keep advancing the spark until it does.What this means in performance terms is that, if the owner uses premium or race gas on weekends, the engine should make considerably more power and torque than the numbers quoted here, which are the product of standard SAE dynamometer laboratory testing procedures and not real-world driving.

They sat down with 3 Ford Engineers and wrote this article, here is a link to it ...
http://www.musclemustangfastfords.co...ine/index.html

Show me a quote from another article that states otherwise.

Doug

 

Oh yea, that'll make a difference ... Nitrogen in tires is a scam !!

Do they guarentee that they sucked every bit of regular AIR out of your tires before they fill them with nitrogen ??

Factory fill was 38 PSI and I lowered to 35 (what the 16" tires on my '04 req'd).

I later read the door jam and saw the 32 PSI ... but am happy with the ride, handing, & braking performance at 35 so I figured the few extra PSI may be working in my MPG favor.

Doug

 

One way to find out if the higher octane gas is doing you better or worse in the end money wise is to figure out your cost per mile of your fuel. I have been doing that lately. To do this take the price per gallon and divide it by your mpg.

$2.50 ÷ 30 MPG = ¢8.3 per mile!

 

Update ...

Filled up today ... 409.2 miles / 12.967 gal = 31.55 MPG ... 2nd best to date.

At the time of fill up, computer was showing "52-MI to E" and "29.6 AVE MPG".
Total miles on car to date is 8282.2.

Here is a summary of my commute MPG to date:
WEEK 1: 28.81 MPG
WEEK 2: 29.10
WEEK 3: 29.46
WEEK 4: 30.89
WEEK 5: 30.99
WEEK 6: 30.53
WEEK 7: 31.47
WEEK 8: 31.00
WEEK 9: 31.67
WEEK 10: 29.90
WEEK 11: 30.80
WEEK 12: 31.11
WEEK 13: 31.32
new since last post:
WEEK 14: 30.38
WEEK 15: 31.37
WEEK 16: 30.88
WEEK 17: 31.56

O/A ave. MPG since new is 29.51 ... but O/A ave. since I 1st broke 30 MPG is 30.53 MPG (both still improving little by little).

comparisons:
O/A ave. for my 1994 Stang (3.8L 5-Speed 145 HP, bone stock) was only 27.92 MPG.
O/A ave. for my 1998 (as above but 150 HP + many mods) was 26.62 MPG.
O/A ave. for my 2004 (as above but 3.9L 193 HP + many mods) was 26.07 MPG

Doug

 

God I get like 240 out of a tank on my 2000 V6 auto. Of course I drive aggressively and have 275s, so that doesn't help. But still. Wow.

 

Great gas mileage Doug. I run 35 p.s.i. in my tires too. I just turned 1,700 miles on my Mustang

 

Looks like after three tanks the engine was pretty much broke in. YOur mileage is impressive to say the least. I just wonder how much difference the 3.31 gears would make. Is there a rpm chart anywhere for the 3.7?
What would the 3.31 gears in a 6 speed manual run at 75 mph? Seems like a big gap in rear gears compared to the GT's.

I am worse than a women looking for new shoes thinking about a daily driver and your thread has made me think about a base Mustang. I just dont know if I could live with 2.73 gears. My driving is mixed and I have never had a car or truck I thought that was geared to low. I would love to know the real world difference in fuel economy and performance.

These V6 stangs are impressive for sure.

 

Not sure how useful this is as a comparison, but I have a V6 automatic with 3.31 gears. My commute is around 40 miles each way with around 15 city and 25 highway. I never use the cruise control. My highway cruising speed is typically 80ish. I use exxon 87 that has 10% EtOH in it. I have around 3800 miles and have been getting between 25.5-26.5 mpg since I got the car. I could definitely get a few more mpg if I slowed down a bit and used cruise control.

 

I drove a V6 manual tranny car with the 2.73 gears the other day and while I am sure that the 3.31's will make quite a difference, I can tell you that the acceleration even with the 2.73's is really something.

 

I'd sure like to see what a car like yours could do on a long highway run with the cruise set at 65. See how close you could get to 30 mpg.

I'd especially like to see what a manual trans 3.31 car could do like that.