Has F1 proved the Prius is a lot of lies?

[xpensive]

Let's try it this way Giblet, if your vehicle is 1000 kg and travels at 30 m/s (108 km/h),
it will carry a kinetic energy of 1000 * 30^2/2 = 450 kJ or kWs

If you bring that car to a standstill in 90 meters at a constant de-accelleration, it will take you 90/(30/2) = 6 seconds
and your "braking-power" is 450/6 = 75 kW (100 Hp) during that time.

But remember, if you want to recover that energy, locking the wheels is a no-no.

[xpensive]

When my sketchy xample upstreams on this thread, suggested that you could save yourself some 500 liters of gasoline over a 5 year period with the Prius, I just wonder how much xtra you have to pay for the recovery gadget?

[Gecko]

Weight itself does not cost energy.

Depends on whether your going up hill or not.

But that was my whole point. You spend more at the same weight, but this is also the energy that you can recover when braking, or going downhill.

[Richard]

You spend more at the same weight, but this is also the energy that you can recover when braking, or going downhill.

Not quite, what about friction and efficiency? More weight equals more energy lost?

Here's an example.... I was on the Jungfraujoch railway in Switzerland last summer and that has a 1,393m ascent over just 9.km. Their brochure proudly stated that ntheir new rolling stock has regenerative braking. However the energy regained from braking going downhill is only 1/4 of the energy expended to go uphill. Given that it is on a cog rail (so neglible slippage, and is a continuous steep gradient I'd have thought that would be at the top end of effiency. How deos that compare to a hybrid road cars?

http://en.wikipedia.org/wiki/Jungfraubahn

[Gecko]

You should compare two situations; a slightly heavier car that can recover at least some of the energy (I think at least 50% is easily achievable) or a somewhat lighter car that can recover none. In the end, you have to consider the typical driving profile (city, motorway, hilly terrain) and figure out whether it's worth it on overall balance. A hybrid motorway cruiser is pointless. A city car can easily be worth it.