I live in sunny Nothern Minnesota it's 3 above right now !
If I had a heated garage like the guys that married my exwifes. I'd be under my truck now to see about adding some tail pipe just to quit it down till I swap in a slant 6 next winter. I'll have heat then or another ex with a heated garage!

 

Dang that's cold. It's probably 40 here. I love my slant. Has no power. Lol. But it's pretty loud just straight piped. I want a cherrybomb so I can say I have something muffling the exhaust if I get pulled over.

 

93' W350, 360 Multi Port Fuel Injection.. 4.10 Gears.. 8-10 City, 14 Highway at about 65-70

 

I posted here before saying I was getting 12mpg. Now . . . I've lightened my foot a lot, which is hard for a stupid 18 year old to do, and have chopped down the air filter lid, and threw on a glasspack. And I now happily get 14 mpg

 

Stock 79 W200 Club Cab, Long Bed, 360 V8, 727, 3.54 gears, 285X75X16's, 6 to 12 MPG, depending on situation. 10-11 average on highway.

 

Just got my '92 W250 ext cab 4x4 on the road. 360 TBI, 4 spd OD auto, 4.10 gears with 33x12.50/16.5 MTs.

Averaged 19.5 MPG empty on the highway over a 120 mile stretch @ 55 MPH. 14 mpg city. I think adding locking hubs, and an MSD style ignition will bump me up to around 21. Much better than I expected.

 

My 86 shortbed 318 np435, true duals dumped in front of rear wheels, all emissions crap trashed, and oversized rear tires got around 16 city and 23 highway. (though it probly was a little lighter than stock due to all the rust lol)
The completely bone stock 87 318 auto I just bought gets even better mileage since it don't run yet!

The only reason I can think of is that the flatbed may be lighter than the original. Decreased weight=increased mpgs every time. Why do you think all these new cars are 90% plastic?

 

I have a 92 W250 with a 360 TBI. It has 4.10 gears on 285 75r 16 tires with a NV4500 tranny. Smog pump belt off, no catalytic converter and all stock internals. It has Accel wires, E3plugs, 2 1/2 to a Y pipe to 3 inch single out Gibson Exhaust out the back, and K&N in a stock air cleaner housing. It gets mid 13s to low 14s now on the highway. I have had it for 8 years up until now gave me 12 to 12 1/2 pretty consistently up until resonantly. That is driving reasonably all those years. Check coolant temp senor to see if faulty, it will make you run rich. That seemed to help me.

 

Here's my way to get an accurate MPG. I have an Android phone with a GPS and an app that tracks, very accurately, average speed and distance traveled. So fill the tank. I know it costs but you'll have to spend it anyway. Turn on the app and drive fifty miles or so as normal. App will tell you just how far you traveled and the average speed for that distance. Fill er up. Miles/gallons= MPG Highway miles, same deal. I imagine iphones have the same kind of app.
Don't call 'em smart phones for nothing.

"If I would've asked people what they wanted, they would've said 'faster horses'." – Henry Ford

 

I am getting about 16 around town and 18-19 hwy, but still more tuning is necessary. This is in a fesh 318 powered 1980 W150 shortbox. Ive got 360 heads and magnum pistons around 9 to 1 compression. NP 435 trans and 355 gears. I am using a Q-jet and factory intake. need to recurve the distributor and do some carb mods and also install an O2 gauge. runnung the 235 75R15 (goodyear wranglers). truck weighs 4700 lbs. All in all I am happy.