You put your reg in from your car and it comes up with your cars info 
Also it reminds you when your MOT is due and your tax etc
Much if not all of that info is available already.
The point about granting access to your phone data is a good one.
I would be concerned if the app like this asked for access to location (gps) information on your phone and tablet. Same for address book details.
IP addresses are unlikely to get you very far as far as location is concerned. They’re not like phone numbers. Blocks are allocated to network operators and even if used on a regional basis won’t say exactly where you are. Only if you have access to the network systems and routers can you get some idea of location of the end device.
Mobile device operating systems are very compartmentalised. Software has to ask for permission via the operating system and the user to get access to certain data on your device. When an app asks - think carefully if it it necessary for the app to have that data. If you’re unsure, say no. Most people will just click yes to get rid of the annoying box!
Choose apps that have lots of stars and reviews.
Apps in Apples Store undergo more rigorous testing but could still ask you to grant access to your data.
Treat apps for Android a little more carefully. The operating system is as good but it’s easier for rogue apps to be pushed out.
As suggested earlier, only grant access to your address book for things you want to have access. Things like Facebook keep asking for access because they claim it helps them find your friends for you from that data. That may be so, but, they still have your data and they will sell it on.
It is a nuisance having to go into the setup for each app but worth it to keep your data secure.