>> [Actually, having computed that my car uses 10^(-6) L of fuel per 
>> minute even when it's flying down the road at 75 MPH, I wonder just 
>> how much fuel it can possibly be wasting on tickover? And also, 
>> doesn't repeatedly starting up a petrol engine waste fuel anyway?]
>>
> 
> I'm having trouble with that math, but it could be that I haven't looked 
> at a diesel car in a while.

Don't worry about it. I plucked 10^(-6) L out of the air. My point was, 
during recent calculations it showed up that just coasting along uses 
surprisingly little fuel. (I calculated that the amount of fuel injected 
into each cylinder is drastically less than 1 drop. Which, obviously, is 
impossible. The fuel would have to be vapourised or something, otherwise 
surface tension would simply prevent you injecting such an absurdly tiny 
volume.)

My [petrol] car can to 75 MPH at roughly 45 MPG. Let's do some math...

75 miles/hour = 1.25 miles/minute.
45 miles/gallon = 204 miles/litre.
204 miles/litre = 0.0049 litre/mile.
1.25 miles @ 0.0049 liter/mile = 0.0061 litre.

So we have roughly 6.1 * 10^(-3) L/minute. That's 6.1 mL per minute. 
That's, like, one teaspoon of fuel per minute, while rocketing along at 
75 MPH. What the hell the engine uses while idling has surely got to be 
even smaller than this...

>> Last I heard the car never came to market. They were still playing 
>> with the control software to try to figure out the most optimal 
>> algorithms...
>>
> 
> They have gotten it working, the Toyota Prius does just that. It can run 
> on the electric motors up to around 35 MPH, and cuts the petrol engine 
> off when ever it doesn't need it. The batteries for the electric system 
> charges off of both the petrol system and a regenerative braking system.
> 
> What's really odd is riding in one of these cars when the petrol engine 
> cuts off at highway speeds. The car just decides that going down hill is 
> easy, and the driver is braking anyways, so who needs the engine?

The reporter I saw remarked how eerie it is when you pull up at some 
traffic lights and the engine goes silent...

Personally, it still kinda weirds me out that when a train is about to 
get moving, it makes this loud whirring noise, and starts moving, and 
then the whirring shuts up and the train accelerates MORE. o_O

[Of course, the noise you can hear is actually the hydraulics for the 
brake system or something - it has nothing to do with the more or less 
silent motors that actually drive the train along.]

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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