[brucepick]

From http://ecomodder.com/forum/showthrea...tml#post333966

Originally Posted by Nerys

unless you do hard core city driving (block to block stop and go) or mountanous terrain without ability to EOC. then mass has very little "realized" effect on fuel economy.

I massed 455 pounds (440 now :-) I used to be even heavier.

sister is 350 plus my 200 pounds of crap.

drop off sister and emptying the car has almost ZERO measurable impact on fuel economy

an object in motion remains in motion till acted upon by an outside force.

IE once your "going" at whatever your cruise speed is mass has almost no further impact.

mass only really comes into play during a change in velocity ie accelerations but only positive accelerations (speeding up)

this includes accelerating to a higher speed and "climbing" (which is a vertical positive acceleration even if your not changing speed your Vspeed is changing)

so for many of us steady state highway semi highway cruisers mass is irrelevant. what we want is minimal drag and lower rpm (larger tires)

now you city drivers its a different ball game. you want TINY tires to reduce acceleration loads aero is completely irrelevant and mass is EVERYTHING.

SO if your a cruiser you going to switch to 155/80/13 tires and aero the crap out of your car.

if your a city crawler or mountain crawler your going to want the original 12" tires and you want to STRIP the car of all non essentials.

I am a cruiser so the extra mass of another battery is literally irrelevant and immesurable on my fuel economy.

however the HUGE difference of removing both the alternator and water pump from the equation should have a pretty large impact on fuel economy.