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      12-29-2007, 04:35 PM   #67
Lieutenant Colonel

Drives: Legacy GT - 13.704@99.39
Join Date: Jul 2007
Location: Manheim, PA

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Originally Posted by swamp2 View Post
I have heard it will not be in the US as well but certainly have not heard that officially. I hope we get it, a very nice feature - good for some definite hp to the wheels. So even though I have heard the rumor I am either assuming it is not true or just taking a best case scenario based on the features of the EU car (even if it is not the one I will get).

-Charcoal filter ~10 hp at the crank
-Regenerative braking ~5-10 hp at the wheels

We could be looking at about 20-25 less hp at the wheels for the US car, UGH! I suppose this is worst case scenario but since the rwhp is "hidden" and all BMW has to quote is crank hp it is just another way the US gets screwed and gets a slower car, double ugh.
I thought we had already discussed some of this? Oh well.

Assuming regenerative braking is shorthand/marketing talk for disabling the alternator during hard acceleration so no power is lost to charging at that point, what are we really talking about here?

Assuming 125 amps at 14 volts max charge rate, and also assuming around 80% efficiency (alternator will be well over that, but some power is lost to resistance in the wiring), we're talking, what, three HP?

Now assume well under a third of that number unless you're running A/C along with the rear window defroster, seat heat on extra crispy and that aftermarket boom box in the trunk during your drag race or top speed run.

Now multipy that by 85% to get the rear wheel number...

...and you discover that two healthy hamsters can generate that amount of power.

OK. Three hamsters.

OK, now figure (and here's the real point we discussed before) that the SAE is already on board with this for the ratings run.

Either way, we're talking a dimple on a pimple on a flea's left nut. It just doesn't matter.

Charcoal filter? I must've missed that. How will that be worth 10 HP and why won't the SAE be informed?