Best magnum MPG?

273 said
I agree real world gains are small that's why it's not worth spending too much money on improving fuel mileage it's hard to recoup the cost. But weight does make a difference especially intown driving. The resson gains aren't huge cause for huge gains percentage wise is actually small in actually mpg numbers.

My 5.9 jeep gets 12.5 mpg average. I would imagine it would at least get 15 mpg in my cuda that's a 20% increase but actually equals to a 2.5 mpg increase and that's a 1500 pound difference.

All I was trying to say is it takes a certain amount of hp (fuel) to move a certain weight and aerodynamics that's why I said ultimately. Over 20 mpg in town would be hard and expensive.

My point is real world gains don't exist and it's foolish to account for that over gear ratios within the transmission, axles, chassis and aerodynamic characteristics, engine fuel demands, and available torque. I'm not discussing in-town. That's far more heavily dependent on driving style, idling time (i.e. traffic), and as such usually not very comparable in my mind.

The thing is if you compare a 4000lb car to a 2900lb car with the same everything those differences marked are rare. Same when comparing a 2900lb Jeep to a 4000lb Jeep- often the economy's just about the same. Same motor will typically do a bit worse in a Jeep, a bit worse than that in a full frame Jeep, and than even worse in a full frame truck. That doesn't mean it'll have to do horrible, but it will do less. By the time you're typically talking of the utilitarian barn-door aero designed full size truck it's typically far lower, even if that full size truck is 200+lbs lighter than the car.

magnummopar said
Factory manufacturers have spent millions of dollars trying to get any advantage when it comes to mpg. They spend millions of $ and tons of time in wind tunnels making bodies more aerodynamic so you get better mpg. If vehicle weight made a huge difference, they would spend more time on a scale and less time in the tunnel....its all about aerodynamics, much more than weight. The weight factor comes in when you are talking about puny engine like aprius that simply cant push more than 2500#s. In a V8 with lots of torque, its the profile of the body lines that matter most.

That I completely agree with. And I'll add I'm impressed you've seen 20mpg out of Wranglers. I think that's also why they've all pretty much gone to these VVT style setups so it'll cut power at cruise but it'll have the power under load to perk the maxes up even though they may be totally unobservable.