Is there anyway to not automatically turn the system on upon starting the car or turn it off as a whole?

As long as the car is turned on, the unit will be powered on. The only way around that would to be putting a toggle switch on the radio's red (ACC) power wire.

that's annoying... I'd never thought about it but sometimes I like peace and quiet in my truck! Is this a common "feature" of nav systems... no power off button?

Just press the source button on the top left hand corner and source it to off. It will stay that way until you switch it on. You will however still get turn-by-turn guidance even when sourced OFF

Just press the source button on the top left hand corner and source it to off. It will stay that way until you switch it on. You will however still get turn-by-turn guidance even when sourced OFF

Not if there is no route programmed.

If you don't want the unit making noise:

1 - got to the source screen and hit the off button which will turn off the A/V portion of the unit.

2 - Delete any currently selected routes.

The bluetooth function will still work this way if you get or need to make a call.

Pretty sure people know it doesn't announce turns without a route plotted

You are giving people way too much credit. The human race in general, especially these days, are a pretty dimwitted bunch.

you can do it on the kenwood dnx5120 but if you need that much peace and quiet your truck might not be the spot

At off, will the screen still be on? The light can be disturbing at night... at times... lol

Yes, but you can turn the screen completely off too. Its in the settings menu...under system if I remember correctly

At off, will the screen still be on? The light can be disturbing at night... at times... lol

so your options to turn the unit off are:

without a toggle switch: Turn off any AV source on.

Delete any current route programmed

press screen off in system settings

-or-

with a toggle switch: flick a switch.