Modern is a subjective thing. I have a golf 5 from 2005 (tdi). One day I had to go somewhere and it turns out the car starts and shuts itself down immediately... It turns out the ground connection to the dash was intermittent. The dash for some unknown reason is the place where the immobiliser code/certificate is stored so when you start the car the Ecu has to talk to both the immobiliser coil next to the key and the dash.

I'll leave it to readers imagination how long it took me to troubleshoot the issue.