When do I know when to downshift using the paddles? I don't want to blow the engine.
2016 c7 1LT. Picked it up yesterday. Can we coast in second gear if so what rpm?

 

The car's software will not allow a downshift of the automatic transmission if the result will be an overrev of the engine. If you attempt it, you will get a message saying "Shift Denied".

 

I have see. That. But in M mode I have downshifted and seen the tach go in the red. Isn't that bad?

 

Is your C7 still in the 500 mile break-in period. If so the tach shows a lower RECOMMENDED redline for this period of time and you should follow it. The same is true even after the 500 mile break-in when the engine is cold you will see a color band with lower yellow and red segments that will move up as the engine warms up. This temporary lower limit is a recommended redline and you can exceed it but NOT the true recommended speed for a broken-in engine.

The A8 software won't allow you to select either too high or too low of a gear that would either lug the engine or send it into over-speed. If you try to leave it in too low of a gear while accelerating the engine rev limiter will be engaged. The only case where you MIGHT be able to exceed safe engine speed would be to select a low gear on a steep downgrade and then not use the brakes allowing momentum to push the engine past recommended RPM; I don't know how GM has that area programmed and I am definitely not going to test it. But it will not let you select a lower gear at too high of a speed and you will see "shift denied" flash on the DIC.

If you are in the initial break-in I would drive the A8 in manual mode to keep AFM (active fuel management which shuts off cylinders under light load) from activating but shift to keep it in the recommended break-in operating zone. Even in manual mode the A8 will still downshift as needed when stopping so in non-spirited driving you can let the software handle the downshifts while you handle the upshifts. Avoiding AFM will ensure that break-in is even across all 8 cylinders. My 2016 Z06 was a museum pickup and I drove it home in manual mode which is where it stays almost all of the time.

 

Sounds like you may not want cancel that extended warranty.

 

lol I'm going there tomorrow don't jinx me. I have to fight the jerkoffs while they try and convince me to keep it.