I dunno, Comcast still exists regardless of what people think about them. Reputation is a thing but I don't think it's a make or break attribute of a company in most scenarios.
I'm think on how something like this would play out at a drag strip, arguably the place where a claim of 10.9 means the most. I just don't see some random passerby person making a purchase decision based on me being upset about my car not getting a 10.9. Honestly, I would look like some rich asshole who can't drive his car. Conversely, lets say I gave someone a test drive and then told them that I thought it would be faster because "Tesla said so." They would look at me like I had grown a second head.
At the end of the day, the only way this gets fixed is through competition. Tesla business practices are less than stellar across the board. They repeatedly miss product launch and delivery targets. On a large and small scale what they promise to deliver is largely different from the reality. They miss revenue estimates consistently. They have had a single year of positive cash flow in the last 10. Tesla survives because no other company makes a product that comes close to what Tesla has. Until that changes there is no business incentive to be accountable to anybody. The people here who are unhappy have no recourse but to complain to people here who may or may not care.