Ok so what rpm are you guy's engines running at those speeds?

Remark, thanks man

 

Mine gets the best mileage when rpms are below 2200 or so.. So I try to stay between 70-72 (I dont use cruise). Thats on a two door sport with 225s and 3.21 gearing.

 

At 70-75 i'm holding a steady 2,000 RPM. At 65 i'm at about 1,700-1,800 RPM.

I have not experimented with turning over drive off. I hear that since the engine doesn't have to work harder to stay in fourth gear, it gets better mileage. There is alot more acceleration with OD off, but idk about mileage... I'll experiment with it sometime. in the mean time i'm sure somebody else has.

 

On flat highway my stock Rubi gets 19 at 70MPH. Sorry never really look at the RPMs.

 

Most cars are most fuel efficient around 40mph

 

The 3.8 is most efficient when its in a Dodge Caravan.

 

2500 is too high for efficiency. Just over 2000 would be good for flat highway.

 

I have determined that the Most effiecient that the 3.8 gets is when the engine lift drops it to the ground and the lift picks up a v8, any v8.

 

When it's off.










All kidding aside,

It really is not all the engine's fault but rather the horrific transmission combos that just slaughter the efficiency thing here. Guys in Kansas probably do the best flat land travel. Up here hills = abrupt cases of anemia. I am better off than stock with 5:13's and 35's and see an average of 17.6 up hill both ways to work and back. keep o.d off anything 50 and under as lugging really shows off the 3.8 struggle.

 

I don't understand why so many people bash the 3.8. The 3.8 under the hood of my 08 X has adequate power. I do however have a 2dr 6spd, but I have been running 35s with stock 3.21 gears now for almost a yr without any power issues. I can climb steep hills, and maintain 75 plus mph with ease. I also run the superchips 91 tune so helps a bit as well.. Maybe I have a factory freak?