1. Google says it is not true.
Multiple different sources report that google wants that data; going back over a year.
2. Adding things like current speed and wheel angle can really help with dead reckoning when GPS is having a problem getting a lock like going through a tunnel.
"The publication says that Android Auto tracks variables including vehicle speed, throttle position, fluid temperatures, and engine revs, information that is collated and then sent back to Google"
So does it need to be collated and sent to google for dead reckoning? Why can't the phone do that itself? Or maybe the car doesn't need to give all that data to the phone so that it can do dead reckoning because the car already has GPS, antennae, its own dead reckoning and plenty computing power that's not constrained by a tiny battery... so rather than report its throttle position and steering wheel position etc, it can just tell the phone where it is, as a solved problem.
3. Knowing how much fuel you have left and your current mpg can help it find the cheapest gas along your route.
Yes, because saving a nickle a gallon sounds like a typical Porsche owner priority.
Meanwhile Porsches have been able to estimate their remaining range for over a decade. If the phone wants to know if it can reach cheaper gas the app can ask the car if it thinks it can go another 200km or not.
All that said... if Porsche doesn't want to hand the data over, big deal. The android app can just say "Feature not available. Porsche telemetry not available." I don't see why that's not a valid solution.