Nuke

That's genuine. I'll bet you don't use the same philosophy with your checking account.

2007 grimlock stang

Nuke, sadly I don't. I'd never get any of those damn late charges if I did.

tnroadrunr

I have a 2010 convertible with a 4.0 Liter, and 5 speed Automatic Transmission. Just drove from Nashville Tn. to Mobile Al. Put in about 150 Miles intown Driving in mobile over the weekend, then drove home to Nashville. Had the cruise set on 75 Miles per hour all the way down and all the way back. My overall average after I got home was 25.8 MPG.

I would expect a hardtop, with a standard transmission, driving 70 (not 75), and not using the cruise to get substantially better.....

Nuke

I doubt it. Maybe 1-2 MPG but nothing substantial, and that would be more from driving 70 than due to being a hardtop OR manual. Also, the cruise control will HELP fuel mileage providing you're not in hilly terrain and the tranny has to keep downshifting to maintain speed.

tnroadrunr

The aerodynamics of the hardtop would certainly have to make a difference over the drag of the ragtop, While I agree that the transmission probably wouldn't make that much difference on a long haul Interstate run. As far as the cruise goes, I Live in Central Tennessee, there is nothing here but "Foot Hills" and of course they don't just stop at the state line, so a good piece of the trip was purely hills. But the 4.0 has more than enough power to pull the hills without a lot of down shifting.

And yes the biggest increase should be from slowing to 70 as that is the researched break point of fuel economy. After breaking the 102 FPS mark the power required becomes quite disproportional. Even though 75 is only 109 FPS it takes quite a bit more fuel to achieve that additional 7 FPS. Which is why highway fuel estimates are always figured using the range between 65 and 70.

Chris45215

My 2007 V6 auto (no mods except swaybars) gets about 22-23 MPG, 70% highway, but that highway tends to be at 65MPH. I drive conservatively 80% of the time, and aggresively 20%.
A lot of my long-distance trips are at night, and that actually DOES make a difference, lowering efficiency by about 1.5 MPG. (see the wonderful analysis and experiment at http://mb-soft.com/public/headlite.html both the mathematics and real-world testing verify this)

Unless I draft behind a truck at 60 MPH all day, I doubt I can get better than 25 MPG. I plan to try Techron fuel additive soon, so maybe that could make a difference.

Kona6Stang10

East TN however.........

Lol, elevation changes like crazy over here