I have a 04 Dakota SXT crew cab 4X4 with the 3.7 engine, manual tranny and 3.55 rear end. I get around 16 mpg in the city. I recently drove it on a short trip of 211 miles all highway driving and only got 16.4 mpg. I averaged about 80 mph. My understanding was that it should get around 20 mpg, is anyone else getting this kind of mileage.

 

16.4 mpg at 80 mph, Hmm, I'd think that would be pretty reasonanble for most vehicles, let alone a mid-size pickup.

Ethan

 

i think i can beat that doin 75 in my 4.7...doin about 19....

 

You'll probably get the 20 mpg on the highway if you cruise the speed the EPA uses for its tests - 55 mph. That's how the transmission is set up (in my 3.7 auto, anyway). At 55-60, I'm under 2000 rpm. Hit 80 and it's somewhere between 2500-3000 rpm. That's a big difference in fuel useage.

 

Just because an engine is turning fewer revs, does not necessarily mean better fuel economy.
At 60mph in top gear with torque converter locked, my engine is doing 1600rpm and I get about 19mpg.
At 60mph with O/D OFF and torque converter locked, my engine is doing 2300rpm and I get about 21mpg.
Last time I drove from Seattle to Denver and back, I averaged almost 400 miles between gas stops (22 gallon tank).
There's mountains much of the way, and I spent a lot of time with O/D OFF during the uphill portions.
Can't explain it, it's just what I've experienced.

2004 4x4 Club Cab SLT Auto with 3.55 rear and 265/70R15 (31x10.5x16) tires.

 

Strickly in theory, that's impossible on a flat trip though... Through the mountains, you must be running a 6 banger? It seems as though a smaller motor might have to work harder at lower rpms due to the lack of torque. Therefore, pulling your truck up a mountain in OD would require the motor to burn more fuel to produce the same amount of work. Going downhill though, I would bet my truck title that you'de get better milage in OD. Interesting stuff though!!!

 

Oops. It's a 4.7L engine.
The 60mph numbers were for flat terrain.
I'm thinkin' that since the engine's hp and torque peaks are nowhere near 1600rpm, the engine actually needs a bit more gas to do the same work it could do easier at 2300rpm with the different gearing it uses with OD OFF.
Like being in too high a gear with a manual transmission.
Just speculation, though.

 

I have an 04 reg cab SLT 4x4 with the 3.7L that only gets 14mpg no matter what you do....what the heck is my problem???

 

You guys ever try the granny method?
I jumped from 13 to 16.6 with the granny method, but im too lazy to granny it.

 

Btw i have a 4.7 with a K&N and thats it. Its only got the 65mm tb cause its a 00.