will a heavier car coast further?

[Hateful]

I'd rather have a smaller car even though I risk being killed by those with style.

[Lug_Nut]

Originally Posted by RoadWarrior

I think you're confusing newtonian momentum with relativistic momentum. http://en.wikipedia.org/wiki/Relativ...stic_mechanics

At 0.0000001% the speed of light, about 67 mph, I don't think I am. That is close enough to zero, relative to 100%, that relativistic issues are negligible. At 0.00000005% of C, or about 33 1/2 mph, even less so.

Al's elegantly simple mathematical ....

Oh, Sorry, he let his close friends call him Al.

Herr Einstein's elegantly simple mathematical equasion was developed from imagining what might happen if the energy increase seen and measured and calculated at these lowly speeds were extrapolated out to their logical, albeit theoretical, conclusion. The E=MV2 equasion was existant long before he decided to theorize taking velocity to its limit.

[GasSavers_RoadWarrior]

Hmmm but you appeared to be using a newtonian example to illlustrate that mass, energy and momentum do not become infinite at the speed of light.

[Lug_Nut]

They don't.
Mass does not change with speed, whether 0.0000001% nor 99.999999% the speed of light.
Energy in the moving object due to momentum does approach the infinite, but does not become infinite, as the object approaches the speed of light.
In theoretical terms the energy would become infinite if the object were ever able to move AT the speed of light, but the mass of the object would not change.

[8307c4]

Originally Posted by lunarhighway

but the extra weight will take extra energy so i'd like to figure out the best strategy to minimise the loss.

accelerate real nice and easy, really there's not much beyond the already useful hypermiling techniques but I think in a heavier car a heavy foot has a much worse effect than on a lighter car... That is in percents I think it's all the same, but at the pump and in dollars you feel it more with the heavier car, so a very light foot on the throttle and lots of hanging back and DWB.

You know it's all the same loss, whether you go from getting 40mpg to 30 or whether you go from 20 to 15 it's all the same loss here... But get to that pump and the difference is like ok on the first you have to spend 30 instead of 20 (+$10) but on the second example you have to spend 60 instead of 40 (+$20) so it'll drain your pocket book quicker no matter how you look at it, all I'm saying.

Take it nice and easy, best I can tell you.

[GasSavers_RoadWarrior]

Originally Posted by Lug_Nut

They don't.
Mass does not change with speed, whether 0.0000001% nor 99.999999% the speed of light.
Energy in the moving object due to momentum does approach the infinite, but does not become infinite, as the object approaches the speed of light.
In theoretical terms the energy would become infinite if the object were ever able to move AT the speed of light, but the mass of the object would not change.

Ah okay, that argument. I'll just agree that rest mass is always rest mass.

[RightontheMarc]

Someone please tell me why my car coasts worse in the winter than in the summer. My tires are not that much less psi. Is it something to do with the colder grease in the bearings? I can't figure out what the hell is wrong. I'm still getting a crappy 31mpg. I used to be able to coast all the way down this one gradual slope of road without losing speed and going below the speedlimit. In fact I used to accelerate a little. Now my speed drops about 5mph and I risk the cars behind me getting mad.

[GasSavers_Erik]

The transmission fluid is cold and thick in the winter- this really increases drag even in neutral

[dddon]

aahhh yes .. when i was a lad working at a "socony mobil " station ,,, we added ATF to the tranny and rear axel to make the cars more efficent ,,they were ALL stick shifts back then..
and YES! the grease in the wheel bearings adds a lot of drag to a car or truck!! during that era there was the "mobil economy run" .. the teams did all the things that you find on this site AND many other things to make their car get the best mpg they could ... the penalty for an infraction was a full stop !!! .. example: the drivers would grind the heel of their right shoe rounded so it would be smoother on the gas pedal.
so look to the proper alignment of the wheels, and synthetic lube in engine and wheel bearings, as the over the road trucks have done for many years... dddon

[GasSavers_RoadWarrior]

Also cold air is denser, so you'll have higher aero resistance. For example my van takes about 20.5HP in aero to cruise at 60mph in -5C and only 18.5HP at 25C