I’m not sure why so many here are so quick to call for such complex Valet mode settings. Not to mention the additional UI complexity would effectively be wasted effort, shouldn’t the fact that it takes nearly 9 seconds to get to 60 pretty much take all the fun out of Valet already? You really want to be able to stick it to them even further by forcing it to be driven under 30mph and potentially cause an unsafe situation?
I understand what you are saying. Folks here at TMC are constantly debating changes and upgrades. These discussions often result in some pretty fruitful ideas. I think in this case, we are doing the exact same thing: taking a great product and thinking about how we can make it better.
For me, if the Valet mode is truly for Valets, then I would want a max speed of 50 mph. If we were to ask TM to allow this to user adjustable, I imagine that that would be about the lowest it should be allowed to go. I could imagine someone being too aggressive in their limitations and setting it for 15 mph. This could be dangerous.
All in all, I bet TM chose 70 for a reason. Maybe their research showed that this was safest. Perhaps it is not just for valets, but as mentioned above, is to limit the car for when it is loaned out to a younger driver or someone who is not yet ready or trustworthy enough for the full effects of this beast. I could see using it for that (I just have to remember to take the registration out of the glove box in case they still screw up).