Using ble tags to determine if a car should be running or not( Newbie)

Hi everyone!. First, as a context for the project, in my country crimes related to robbing a car while it's running, and driving off with it have been on the rise, there are systems on the market but they cost around 500 usd to install and 20 usd every month you use the system. I thought that using a "wireless kill switch" would be a cheap way to help people recover their cars if they get robbed .
The operation would consist of using a relay(let's call it Arduino relay) to allow power to flow to the pump relay if it detects that a authorized user is in the car.
At first, I thought that rfid would be the best idea, given that it's simple to implement (and that I have some small experience working with it on projects), but very fast I concluded that it simply does not have enough range, my idea is that it can detect a user within a couple of meters, and if it doesn't detect a user, after a certain time, shut off the power flow, killing the car essentially, forcing the criminals to leave the car there and run off.
Ble sounds like a good idea, I have read that it has a range of 25m, that would be a safe distance as the criminals would be away, so as to not come back to the person.
My question is if it even makes sense to use ble, there are cheap tags on the usual sites, and esp32 boards aren't that expensive, but almost everything I've read (which is not a lot) relates to using a phone. Or maybe there's another system that I have not considered for this application
Thanks in advance!

Think of the consequences, and risks to the vehicles passengers, and of cource other road users, if the car cuts out at random whilst being driven, how would you make absolutly sure this could not happen ?

I very much doubt the vehicles insurers would permit such a modification in any case.

if it's a school prototype, propose to activate the horn and flash all the lights instead. The thieves probably won't like the attention.

if it's a real system, you'll quickly see why it's so expensive to build the real thing :wink:

It is permited, and most insurance covers this (mine does, but of course every insurance has gone up because of that).
The systems that are on the market operate like this, you signal with the phone to shutoff the car, while sending the location to the police department.
By law, insurance companies have to provide a gps system, and the owner of the vehicle has to take more actions to combat the situations, like installing a kill switch, or using systems that are on the market.
One of the reasons I asked was because I'm afraid there might be random cut outs, my idea to mitigate this was, if the arduino dosen't detect the tag, for it to check again 30 s later, then again 30 s later, and then again 30 s later, and if in the 3 checks it doesn't detect the tag, to start a timer to cut off the power to the fuel pump, maybe giving a sound cue as a warning.
Edit: Any system instaled has to be complaint and obey regulation 116 of the UNECE

I like this idea, a lot simpler than cutting off fuel for the car.
Would ble work fort this though? As in, can I have the arduino just check if the tag is in it's vecinity, and if it's not, then do somenthing?
Many thanks!

Probably insurance would be fine with certified systems, installed by certified technicians if they touch key elements of the car. That's where the hidden costs are.

You could test for a iBeacon presence using any modern BLE capable arduino. You'll find tons of tutorials on line

here is a couple video (first hit on google)

Thanks! This answers a lot of my questions.
And you're probably right, eventually I'll probably screw up something with the fuel pump system, and I'll write about why replacement parts are too expensive. But with this info I can look a bit more into the project!

The advantage of a delayed shutdown system is that it disables the vehicle after the thief has put themselves in the public view.

Certain interlocks would be desirable for safety, such as shutting down the engine while the car is stationary. Note that many current vehicles actually shut down the engine while idling at traffic lights which would be a quite opportune time, however those vehicles generally already have the key detection system.

So, if I manage to cut power to the pump, would it be desirable to kill the engine when the car is stationary? Makes a lot of sense! I'm guessing I'm going to need to find a way to detect if the car is stopped or not. Thanks a lot!