For emergency responders, you should gather some diagnostic info from the OBD.  

Vehicle speed at impact.
positive/negative airbag deployment. 
for newer cars, seating position sensors where applicable.  This would be good to estimate number of persons onboard (these sensors used for smart airbag systems for airbag control, delta-V from the airbag system (likely won't mean much, but if it can be converted into a usable format, it can be useful to know.

you should back the spark electron and play with that when it comes out.  If nothing else they have a reasonable data plan for like $2 a month, pay month to month.  Another idea, you could capture speed at time of accident using the ODB port (or a GPS)

thanks, I would really consider it. And many thanks for the idea. I will definitely be collecting this data, might as well send it in the sms as well for a detailed alert

https://www.splitsecnd.com

It already exists.

Oh thanks for pointing that out. However this project does not have any man in the middle, the device acts independently. Apart from that it is aimed to be way cheaper as it does not require a subscription. Also, I would like to point out that this device does not collect any data or sends any data unless there is a crash (or the SOS button is pressed).

I am considering a Trigger button to allow for manual activation. This will come handy in cases where no or little impact is registered for example: when a person becomes suddenly ill and is unable to drive. Also if the driver finds difficulty in driving for ex floods and other possible life threatening situations.

Hi and thanks for the interest, I am currently researching into hard foam, it will be placed on the inside of the case. This will reduce the impact on the components. This provides a challenge since I need to make sure the device will not heat up, and proper heat dissipation occurs. The case will most probably be made of aluminum as plastic is too fragile. It should also be placed in the least vulnerable place. I am assuming under the driver's seat will be relatively safe.

Perhaps the location of the box should follow that of other safety devices?

For example, in my car, the airbag control module is located at the bottom of the dash section containing the stereo.

While under the driver's seat may seem like a good plan, it would leave the unit vulnerable to being damaged in side impacts. (or by rear passengers' feet).

You could mount the unit in a single head unit slot, but there is no guarantee that one is available.

The raised driveshaft section between the rear seats might be a good option, provided that the casing is neither weak nor brittle, and that it somewhat aesthetically pleasing.

It would be worth surveying a few cars to see what the best mounting option may be. If you have a self-service auto wrecker in your area, you can usually find a few cars which have been in crashes, although the worst ones often don't make it to the wrecking yard.

Thanks for the tip. I will definitely ask if I could analyze some cars. In the mean time I am doing some research as I think I can find a lot of information in research papers about the subject

what is your plan for black box style hardening to prevent damage in an accident?