I have to +1 the general sentiment that the web browser sucks, and there's really no excuse for it. I've seen ****** android tablets that do a better job on similar hardware. Webkit or no, it's clearly not a current fork of webkit. That being said, the overall UI paradigm is mostly great.
Here's what I would love to see: Apple "continuity" handover tech. The idea being that if you're currently browsing a webpage on your iPhone, an icon shows up on the 17", and you can suddenly get to that exact page with the same text entered via Bluetooth. While handover is currently Apple platform only, maybe this could be implemented using iBeacons (
https://developer.apple.com/ibeacon/).
Or if Tesla built an action extension for their iOS app by which you could manually "push" things to the 17", for example a URL from your current webpage, a route from the maps app, etc, that would be pretty great. That would do away with the greatest disadvantage of the 17", namely that it's slow and nowhere near as pleasant to type on as an iPhone (though better than some android devices), and would take advantage of its greatest strength - display size. As long as the browser is standards compliant first of all.