Untrue. They aren't monopoly rents but they are rents. Can you get better performance from your Mercedes EV through another provider? No? It's rent.
No, but you can sell it and buy a Tesla. Having more features is just "selling a better product". By that standard any optional feature on a market-leading product is "rent-seeking", and that's silly. Is the App Store rent seeking? Is selling junk on Fortnite rent seeking?
No, that's just "selling products". Rent seeking is a specific form of market distortion, and the concept just doesn't apply to consumer products. It's about stuff like real estate control or regulatory capture. As always Wikipedia has a great page: https://en.wikipedia.org/wiki/Rent-seeking
The feature has already been developed, I have already downloaded the software to my device. It would cost the developer nothing, deny them the use of nothing, require none of their resources for me to use the feature and yet they charge for it.
How is that different?
I think the "it's rent-seeking" position would be weaker for toggling entire features on and off—the specific example of unlocking better acceleration was them adding a worse mode just so they could charge a subscription for the better one.
That's not rent seeking. Rent seeking is when an entity has control of something that can't be traded in a liquid/efficient way (this part is important!) and tries to leverage this uncompetetive situation into revenue that isn't subject to market forces.
Cars are pretty liquid. Subscription products are very liquid. If people don't want this they won't buy it. If they don't want cars with this subscription model they'll buy a Tesla[1] or VW. That's exactly the opposite of rent seeking.
That's not saying it's good (or bad) for consumers. But it's not rent seeking.
[1] Tesla also sells over-the-air performance upgrades, but it's a fixed price and goes with the vehicle after purchase. They do have subscription fees for data access features, and for FSD though.