There are ways to make speeding possible while keeping abuse minimal. For example mergency switch that could allow speeding but for example enabled alarm that in normal use would be to annoying and resetting would be neede. There are many ways it could be done in. I believe car nerds could think of something more reliable.
Also do we really know that emergency speeding saves more people than are killed due to speeding? We give such excuses, but are we sure it's really warranted?
So you want a driver in an already stressful situation to be nagged periodically with an alarm that "in normal use would be too annoying" (i.e. during stress, it will certainly be much more annoying)?
That doesn't sound like a good solution.
You could probably work with that by shifting the risk back to the driver: allow the override to work by disabling the entertainment system (few boy racers like driving in silence) and have it blink the lights, play a warning over the external speakers, and text the local emergency number to alert them. If you have a buddy bleeding out in the back seat, you will welcome the attention and the cops are going to escort you to the hospital.
180 is still quite high but at least not completely insane as some of the gangs were before that limit. A number would probably need to be found for any country, state, etc but the tech is probably ready.