i've played with the idea before. i would make some modifications first
- disable, remove or preemptively triggering airbags, including side ones
- remove any sensors to prevent potential automatic emergency braking systems from engaging (applies to very modern cars)
as well as
- disable ESP/ESC, in a lot of cars this can be done with the press of a button
- not wearing a seatbelt
though crumple zones and rollcages are your enemy...
at the end i feel like it just comes down to speed. my personal car should reach up to 270 kmh (170 mph), which i think is guaranteed death, especially with the drastically lowered safety.
but honestly i'm just thinking out loud, it's getting late