In Germany you would need a special permission from TÜV (technical supervisory association) for any modification that has or might have an influence on driving

In Germany you would need a special permission from TÜV (technical supervisory association) for any modification that has or might have an influence on driving behavior. That means that you have to pay them for checking your car and getting a report which allows you to drive it. People are doing this for all kinds of modifications, from custom wheels (where the permission is cheap) to custom engines or suspensions up to completely custom cars (which might get very expensive). Without getting the new permission you are not allowed to drive it on public road. If you still do then you might also have the problem that your insurance is void. I don't know what e.g. TÜV would say about a device like this, but I guess the outcome is it would be either to expensive to analyze it or not possible it all since the overall system design and the interaction between the different devices might be not be known (e.g. there might be no public knowledge on how Acura ECUs might react on CAN signals which were never considered during design).