The voltage going to a spark plug is usually about 20,000V.
A 12 volt car battery can most certainly be felt if you've got a good connection, grab both terminals with wet hands and you'll figure it out quickly. The battery in a cordless power tool could undoubtedly be felt too since most are 18-20V nowadays, you'd just have to make the circuit. Cordless tools are mostly plastic so it seems like it'd be hard to get a shock out of one, but if there's a short somewhere and you've got wet hands I can see how it could be possible.
