Only one EV charger at home?!

I think the energy saving (or lack of it!) is not the only reason for using start/stop. It also saves cars sitting in queues of traffic (eg at lights) with their engines giving out exhaust fumes while the engine is idling. So it's partly an anti-pollution thing.

I wonder how long the engine has to be turned off and then restarted, for it to produce less exhaust / use less fuel than leaving the engine idling. Bearing in mind the energy used by the battery to restart the engine, and the fuel needed to replace this energy in the battery.

I'm surprised that failure of the hydraulic pump would give no brakes at all, because that would be a serious safety issue. Is the pump driven by gears or by belt? Belts can break... I've had the power steering fail on my car when the "fan belt" broke. This drives the alternator and the PS pump. The steering just became very heavy, but the car was still drivable - at least as far as the nearest place where I could safely stop and wait for the RAC. If the brakes had also been affected, it would have been a different matter: the handbrake is bugger-all use at slowing a car down, especially if you are trying to steer with one hand while pulling with all your strength on the handbrake lever with the other hand.

Doesn't take a lot to start an engine. Less than a second at about 200A, so 2.4kW seconds.

Or about 0.6 watt hours. Working on 10KWh per litre of fuel, very roughly, that's around, 0.06cc of fuel equivalent to restart the car.

Sources suggest an idling car engine uses 'up to 2 litres per hour' so lets say an average of one litre per hour.

How long does it take to use 0.06cc? = 0.06 x 3.6 seconds. about 0.2 seconds.

Which suggests that given a decent warm fast starting engine it is ALWAYS worth while cutting the engine when halted.

The downside is that it may not restart, or take time to do it. Not having the engine running in a hybrid situation is what gives them great fuel economy in urban situations, along with regenerative braking.

Makes them no better on a long run tho...

Normally both steering and brakes will be affected, but not to a completely non working extent, by loss of whatever power assistance they normally enjoy.

I remember doing what used to do with previous (vacuum) braked cars on my XJS, Cut the engine before coming to a halt. Nearly ran into the garage! Almost impossible to steer and extremely heavy braking.

I've also seen my brakes 'fade' under prolonged start stop on an M25 queue. The engine simply isn't sucking hard enough to replenish the vacuum after three or four consecutive stops, at idle.

The money you might save on gas you'll spend replacing the starter motor.

As usual kinsey is exactly wrong, as are you

The more you use the starter, the sooner it will wear out.

That's a symptom of a broken brake booster check valve.

You would be suprised because that's not what happens. because the suspension is on the same circuit you have the pressure in the suspension rams available to operate the brakes if the pump is not running.

Mostly where I've looked it was bolted to the end of cam shaft, sticking out over the transmission. (but on the GS it was a single piston pump driven by a cam on the front end of the crank-shaft, the GS didn't have the engine tranverses, but also didn't have power steering so only small pump was needed)

Only a fool is going to going try to limp home in a Citroen with no hydraulic, there's enough energy stored in the suspension rams and accumulators to stop a few times and then you're out. So, if it busts you call a tilt-tray truck or someone with a vehicle trailer.

The catalytic converter will cool off.

The only motor in a Tesla is an electric motor.

Yes, no brakes at all after the accumulator emptied, they are power brakes, not power-assisted brakes. The accumulator is part of the suspension and the brakes are powered from the suspension. From a description of the operation of the system, "If there was ever a catastrophic loss of pressure in the vehicle, for example a failure of the pump, there would be adequate pressure in the suspension to power the brakes enough to bring the car to a stop." When my father's car suffered engine failure, I had to tow him to a garage using a rigid bar, so that I could do all the braking.

Power steering failure can also be a problem. A friend had a company car with a dodgy electrical connection. As he went around a roundabout, the engine cut out and the sudden change in necessary steering effort, with no warning, caused him to hit the kerb, damaging the tyre, wheel and suspension.

Citroens were different. They did not use conventional brakes with power assistance, but used power brakes, with no direct operation. From a description of how they worked, "essentially, the brake pedal is in fact a valve which allows high-pressure hydraulic fluid into the callipers and forces the pads against the disc". So no stored hydraulic pressure = no brakes.

Starter motors have brushes that wear out. Does the Tesla motor have brushes?

That depends upon the starter design. A couple of decades ago, Volkswagen (IIRC), were developing a combined alternator/starter that used the teeth of the flywheel and a toothed ring in the bell-housing. Windings and electronics controlled the magnetic fields, so the two toothed rings could act as either starter or alternator, with no mechanical connection at all and therefore zero wear. I don't know if any cars use similar systems.

No.

I think start-stop gas engines use an induction (brushless) starter/generator.

There are brushless starter motors too.

No, its a symptom of electrically boosted brakes and power steering with the ignition off.

There is no 'brake booster' as such.

No. Very few power motors today do.

Not at my old family home built in 1966, and full of storage heaters. The SEB supplied two 100A feeds (on two separate phases)

My 92 year old mother is still there, and I've been battling on her behalf the chaos of dual phase metering, and E7 teleswitching (before R4 LW conks out, (for what ever reason), with her utterly clueless energy supplier. They say the only solution is a Dual Phase Smart Meter/Switch, but in the same breath say they can't currently support such installations, but in the same breath say 'Hurry, R4 LW is closing next March' SSE/OVO (whose legacy of course goes back to the SEB)

She was rather hoping the problem would out live her, that may not happen !