Quite true> I am much too cheap to pay the dealer $120 per hour for work that I can do much better myself. And that $120/Hr was the last time I looked at the posted rates, 3 years ago. It may be higher now.
And yes, I can do it better for the changes I would seek.

So then it's your too cheap not that a car manufacture/dealer doesn't offer it. So don't blame the car makers for not making cars to suit you, because they can do it.

 

So then it's your too cheap not that a car manufacture/dealer doesn't offer it. So don't blame the car makers for not making cars to suit you, because they can do it.

If something that I wanted a vehicle to have were already available then it would be on the car already.
The fact is that vehicle dealers can and do install aftermarket stuff if folks pay, but usually the dealers that sell that stuff also sell installations cheaper than the dealers do.
Have you EVER seen OEM rear-seat headphone jacks in a car?? I did not think so. Or have you seen an OEM switch for the backup lights, to switch them on without the vehicle running and shifted into reverse?? I don't think so.

 

If You just want to quiet-down the usual noise,
a massive 2-Farad Capacitor, like used with extremely High-Power Car-Stereos,
will do a pretty good job, but only if it's connected with ~6-gauge Wire or larger,
and, You can't mount it under the Hood with all that Engine-Heat,
it has to be mounted inside the car.

Never use the car-body for a Ground connection,
and make sure that the body of the car is well connected to
the Battery-Negative, or the Engine-Block, or both,
with a heavy-Battery-cable and clean and tight connections.
.
.
.

It can be mounted near the front grill so that the air will cool it.

 

A series inductance also works to block electrical noise.
But the systems that I gave seen use an inverter to convert the DC to high frequency AC and then rectify it. That works rather well.

 

Charging with clean DC is more likely to build sulfate bridges and shorten the life of a lead-acid battery.

Really? I've never thought it a problem to charge with rectified-and-not-particularly-well-smoothed AC, but all the stuff I've read tries to make me believe that smooth DC is better. What's the reasoning? I'm really interested to know (mainly to silence the critics)

 

The disadvantage would be the size and cost of capacitors able to do an adequate job of eliminating all of the ripple. so it is not so much a technical disadvantage as a cost and space disadvantage.

 

Have you EVER seen OEM rear-seat headphone jacks in a car??

See them every day. Mine has them. Two, one each side.

an OEM switch for the backup lights, to switch them on without the vehicle running and shifted into reverse??

Mine has bright red rear lamps switchable on at any time, plus the white ones that come on when in reverse.

 

But you NEVER see an OEM switch that kills ALL rear lights, and the side marker lights as well. That is part of the "Bootlegger Setup" that is used for some activities. It is not safe to be activated in traffic .