The kill switch already exists, they just can't use it without advertising it. If you've got a GPS in your car, you've got a kill switch. But in order to work it has to receive a satellite signal. The car can function without, else it would stall when you drive through a tunnel. So simply unplug your GPS satellite antenna and learn to navigate the old fashioned ways.

Yep I'm a fan of older cars myself, (non-SUVs). I've got a '96 Taurus SHO and a '97 Taurus GL, the first for fun, the second for reliability, in spite of it's age the latter only has 66k miles on it.

Not room under the Taurus hood to add much of anything. V8 in that tiny engine compartment doesn't even leave room for LED headlight ballasts.

Incidentally, I do not understand the HHO bit, since it takes as much energy from the alternator to electrolyze water less ~50% efficiency, and then you're only going to get back approximately 30% of that burning it.

I'm sorry but you dismiss physics as if it's not important. Try this, don't bother to convert to HHO, just add water. I had a '68 Rambler, stock got about 16 MPH city, 22 Highway, and was under powered and prone to knocking even though it had only 8.5:1 compression ratio. Added an Edlebrock water injection kit, milage now 22 MPG city, 30 MPG highway NO knocking and WAY more power. No HHO just water vapor, and I expect that's all that's really happening with your HHO setup. Water vapor boils at a low temperature even compressed relative to combustion, so converts more of the combustion heat into expansion pushing the piston instead of heating the block.

@Dennis Wilson (Pureblood) Yes I understand the difference, but as soon as the HHO combusts, you got water vapor so you're back to water vapor injection, and while it might add energy of combustion, it subtracted at least 2x that in alternator load.

@Dennis Wilson (Pureblood) Yes but it combusts into vapor and then the vapor aids expansion. The combustion does not add any energy not subtracted from the alternator. Chemistry and physics do not allow it.