How do hybrids perform so well? MPG AND MPH

So 1kWh of heat energy to run 1.6 mile?

I suspect, based on what I can observe from mine, that the dashboard trip computer shows miles per kWh taken from the battery. It's always a bit optimistic compared with my measurement of miles per kWh going in from the mains.

nib

Fairly close. Especially at low charge rates

-- "The most difficult subjects can be explained to the most slow witted man if he has not formed any idea of them already; but the simplest thing cannot be made clear to the most intelligent man if he is firmly persuaded that he knows already, without a shadow of doubt, what is laid before him."

- Leo Tolstoy

Ah yes! Regenerative braking. Following a Tesla recently I discovered a drawback to the *high braking setting*. No brake light indication that you are about to arrive at his rear bumper.

No distance control on a 12 year old Passat!>

ISTM that the Atkinson cycle could be improved by connecting the piston to a linear motor/generator with no rotating parts and thus no rotational inertia. Under software control and using a battery or supercap for temporary energy storage, the expansion and exhaust strokes could be longer than the induction and compression strokes by, if appropriate, a variable amount. Also, the strokes could have whatever velocity profile, for example, it /may/ be useful to give the initial bang a bit of help to get the piston moving. Who knows, but it seems possible that sinusoids aren't necessarily optimal.

If this is a good idea it will probably have been done.

I thought that was illegal: the brake light must come on under regen

I think sadly that this applies to ANY technology that is 'rediscovered' by the bright eyed and bushy tailed 'we can do it better now' brigade. It certainly applies to windmills. It almost certainly applies to solar panels, it probably applies at least in part to batteries... ...the great struggle is to make it *not* apply to fusion reactors...

I vaguely remember studying the Atkinson cycle and University. And then thinking it wasn't worth thinking about because it probably wouldn't work. Likewise sleeve valves, rotary Wankel engines, H block motors etc etc have all been tried and found - for often quite unrelated reasons to not be as good as a tried and trusted V8 pushrod engine,. Yes, okay today we have overhead cams and variable valve timing, because electronics makes it doable at sane costs, and likewise turbocharging which is as old as WW2 or older is now a good way to get more power out of less engine...but still pistons in cylinders and the Otto cycle rules.

It depends on how heavy the braking is. EU regs are that >1.3m/s2 deceleration requires brake lights. More gentle deceleration (like you'd get from lifting off the pedal or engine braking in a petrol car) doesn't.

Some Hyundais in the US didn't do brake lights at all during regen and were recalled to fix it:

Tested mine on a Renault by rigging up a little light pipe so I could see the high-level brake light in the rear-view mirror. Brake lights came on with regen braking, ie no foot on brake pedal, at a certain level of braking, but only below about 40 mi/h[1]. Above that speed, or with the regen mode in "D" (simulating an ICE car) there was no brake light except when using the brake pedal.

nib

Thanks

Yes but ope to better suggestions for the heat value of one litre of DERV

A school boy maths error, so that makes the diesel pretty good as at best it wastes 70% of the heat to exhaust and coolant.

around 10kWh Which at 50% thermal efficiency is around 5kWh per litre..mechanical energy

so 100kWh is a tank of about 20 litres. Very roughly

Does better than that. somewhere in 40-50% if run very low power and lean

I think that was more for big old naturally aspirated diesels. I'd like to see specific fuel consumption verses power on a modern turbocharged diesel.

Anyway it's got me back to thinking about micro chp, if I had an electric car I suspect in winter it would pay me to run a spark ignition engine to charge the car and run my house whilst using the waste heat to heat the place.

Or a gas fuelled ICE to charge your car and power a heat pump to add to the 'waste' heat.

Are we talking about off-grid living? Why would one *ever* want to charge an EV so inefficiently and expensively if one has access to grid power?

Tim

Better. higher peal pressures and temps

Yes. A diesel genny is cheaper than 'renewables' by a long way.

Because a diesel genny running off heating oil or agricultural diesel is WAY cheaper then renewable grid energy.