Old 5 Oh
Well-Known Member
- Joined
- Jan 18, 2014
- Threads
- 24
- Messages
- 2,423
- Reaction score
- 329
- Location
- Wilder, ID
- First Name
- David
- Vehicle(s)
- 2015 GT Premium AT
- Thread starter
- #1
I think I am noticing a phenomenon I saw on my previous car in the new GT. The rule of thumb is that lower speeds and lower RPM lead to better MPG. I think DOHC engines may take limited exception to that.
In 105K miles, I ran enough gas through my 3.5 V6 to be completely sure it got better mileage at 65 or even 70 than at 55 or 60. The tipping point for that car was about 61 mph, or 2,000 rpm, where it seemed maybe the high-flow heads "woke up" and got more efficient, overcoming the extra air resistance at the higher speed and perking up mileage.
In six or so tanks, it seems the GT is behaving the same way. My highest tank so far is the 26.5+ from Truckee to Winnemucca, which includes about half at 72 mph and about half at 83 mph. I80 is a pretty fast road in Nevada, with a 75 mph speed limit once you are east of Reno. The tank from Winnemucca to Boise at 70-75 mph is higher yet on the computer, though I haven't filled it and calculated it by hand yet, it looks like it will be about 27.5 or 28.
Earlier tanks with a lot of 60-65 cruising were around 24-25.
I am interested to see several things. One, is this just the engine breaking in (up to 1,800 miles now)? Is this real? Are others seeing anything like this? And most interesting (to me) do the 3.55 gears (versus my 3.15s) maybe even help get the Coyote into a more efficient rpm range at normal freeway speeds?
I ask that last because Dabko is seeing some really big numbers with his 3.55s. If that's the case, I have to eat a lot of crow because it will mean life has really changed. With the old 5.0 Windsor, every lower rear gear cost measurable mileage. With this new one, that may not be so much the case. Not that I bought this car as a hyper-miler, but I think these are really interesting engineering questions. Certainly the flow characteristics of the Coyote are much different from the Windsor, so maybe there is unexpected change going on here.
Bottom line: I cannot complain or even whimper about averaging over 26 mpg for the road trip I drove yesterday. That's just miraculous given the 435 HP and the size of the car. Just trying to learn something.
In 105K miles, I ran enough gas through my 3.5 V6 to be completely sure it got better mileage at 65 or even 70 than at 55 or 60. The tipping point for that car was about 61 mph, or 2,000 rpm, where it seemed maybe the high-flow heads "woke up" and got more efficient, overcoming the extra air resistance at the higher speed and perking up mileage.
In six or so tanks, it seems the GT is behaving the same way. My highest tank so far is the 26.5+ from Truckee to Winnemucca, which includes about half at 72 mph and about half at 83 mph. I80 is a pretty fast road in Nevada, with a 75 mph speed limit once you are east of Reno. The tank from Winnemucca to Boise at 70-75 mph is higher yet on the computer, though I haven't filled it and calculated it by hand yet, it looks like it will be about 27.5 or 28.
Earlier tanks with a lot of 60-65 cruising were around 24-25.
I am interested to see several things. One, is this just the engine breaking in (up to 1,800 miles now)? Is this real? Are others seeing anything like this? And most interesting (to me) do the 3.55 gears (versus my 3.15s) maybe even help get the Coyote into a more efficient rpm range at normal freeway speeds?
I ask that last because Dabko is seeing some really big numbers with his 3.55s. If that's the case, I have to eat a lot of crow because it will mean life has really changed. With the old 5.0 Windsor, every lower rear gear cost measurable mileage. With this new one, that may not be so much the case. Not that I bought this car as a hyper-miler, but I think these are really interesting engineering questions. Certainly the flow characteristics of the Coyote are much different from the Windsor, so maybe there is unexpected change going on here.
Bottom line: I cannot complain or even whimper about averaging over 26 mpg for the road trip I drove yesterday. That's just miraculous given the 435 HP and the size of the car. Just trying to learn something.
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