A guy I work with had the in dash info center, do he's been able to figure out what highway speed offers him the best mileage (63 *or* 79).

I've got a 2005 XLT SCrew 5.4 4x4 with towing package (that's as close as I get to knowing the gearing). Anybody with the same truck know what the sweet spot is out on the highway?

 

With towing pkg gears should be 3.73. If you have a rpm guage keep it under 2k. There are sweetspots but general rule of thumb is slower = better mpg.

 

Oh, I drive plenty slow, but I really wanna know that sweet spot. The point where your rpms and your speed are perfect. I can do 900 rpm at city speed, but it'll take too long to get anywhere and I lose money.

Also, I'm curious where the shift point is between 2nd and third. in my '93 Chevy it was 37 unless I was haulin ***. I like to stay right above that point in town. Any idea where it is?

 

Most people seems to agree 2K-2.1K rpms highway seems to be the sweet spot for best mpg. In addition to that, use cruise if you have it, get rid of unwanted weight, keep up on maintenance etc, including tire pressure.

If you're talking around town, that's a different area particularly if you've changed out tire size or width, etc. Those mods can change where the effective gear ratio (larger diameter tires effectively lower your gear ratio, wider tires increase rolling resistance). If you've changed them, you may need to consider changing gear ratios to get you back where your engine is making it's best torque.

I have 2 trucks: 97 SCab SB 4.6 3.55 LS rear and a 07 SCab LB 5.4 4.10 LS rear, both are 4x2's. I've gotten 20 mpg out of both on the highway (2k rpm's using cruise) and 15-16 around town, speed limits on the main stretch I drive averages 40-45 mph, this is in stop-and-go areas. Both trucks are virtually stock. I've dumped most of the excess weight and keep up on maintenance on them. I've also found I do a little better on mileage if I use Shell or BP gas (both seem to like them best)

 

To start, we don't have any Shell or BP stations here. 95% of the time I fill up at Quik Trip.

Going on... on the highway, I usually keep it around 1800 rpm (about 62 mph in all speed zones) but I live in KS, where the wind isn't a possibility, but a guarantee. Even if it's only 5-10 mph wind, it WILL be there. If the air is still, seek shelter. But anyhow, I usually average (all driving) 14.5-15 mpg and I'm driving 75% highway. The maintenance has been immaculate, including the last owner who always took it to the dealer (so I've got the dealer records to prove it's been good). It's only got 42k mi on it and I rarely get into it, so I'm becoming rather desperate to find a solution for my fuel woes. If I can't get better mileage, I may have to sell it and buy a car again.

My next stop is to the local muffler shop sometime in the near future for an aftermarket muffler and dual pipes, but I can only expect so much from that. I'm not particularly keen on CAI or a programmer because changing those kinds of things can make the engine run hotter and I'm not really big on adding undue stress to my engine and it's components.