I am a test engineer by profession and title. I will stick with my estimates. You are totally off since you have no idea what it takes to test a unique system that must be setup to specific test conditions and verified that no hanky-panky has been installed that may fake test results.
So you’re telling me that you don’t have the aptitude to run tests with a device on the vehicle, then remove that device and and run more tests, then compare the results. Somehow, that doesn’t surprise me.