'98 ETC Black 90k miles
My alternator puts out about 13.5V at idle (just checked not a minute ago) and is steady there. Sometimes after a lot of highway driving it will decrease to 13.0 or 12.5 if I pull over into a rest area and idle in a parking spot for a minute or two before shutting the motor off and exiting the car. This usually happens on colder, wetter days, and always goes right back to 13.5 after more than two minutes at idle. But it doesn't happen more than half the time. Either way, I agree that the alternator is very important, but Sub is correct that the driver/owner is the most important part. This is why we're all here - to ask questions and share experience.