Ahhhh so you want input to a platform you want to build.
A few thoughts:
Have you Googled it? There are some online services already doing similar things.
If you as an owner don’t trust Mercedes - a large and very well established business which just take such things seriously - with this data, then why would other owners trust your platform with this data?
If one of your primary concerns as an owner is that your data is not safe, accurate and available with Mercedes, how will you assure owners about that their data is safe, accurate and available with you?
If another of your primary concerns as an owner is that Mercedes might make a mistake which has a negative impact on your cars value, how will you make sure that owners don't make the same mistake?
Further still there is a financial incentive for owners to make a “mistake” which has a positive impact on their car’s value, so how would you reassure future owners (buyers) that that is not the case?
How long would you commit to providing a fully resilient and secure service? Some people keep their cars a very long time, and others sell and so will you export the data to new or current owners.”?
How will you verify ownership initially and later when the vehicle has changed hands, to make sure that someone requesting access to records has a legitimate claim on that data?
How will will you monetise it, will it be monthly payments, advertising, selling the data to interested third parties, etc and if you can’t cover costs and the business folds then what happens to the data?
How much would be people be willing to pay for such a service, if they already have digital and paper records, and can photograph and store paperwork online for free through Google, Microsoft, etc?
If the owner doesn’t completely or successfully redact their personal information, who would be responsible for detecting and remediating it, and who would be liable for the risk?
Good luck with your venture