My "96 Delta '88 has 238,000 miles on it, I've had her for 10 years, and I baby her when it comes to working under the hood. When it comes to fluid changes, I do it when it doesn't look right. Spark Plugs, when it doesn't sound right, and tune ups when it doesn't feel right. Ant other "fathers" out there?

That is the only way to take care of your baby!! I don't go by the suggested time to check and change everything, I do weekly and even sometimes daily checks!

Some things you have to check more frequently than what the manufacturer intended for optimal running. It's usually just a generic time frame that doesn't always take into account all the factors. I think you've got the right idea.

I am pretty sure tons of car enthusiasts out there doing a lot more then just changing engine oil or checking spark plugs, How bout doing the modification of ECU ???

For me, there is no such thing as spoiling the car. If we want our car to live longer then we will do our best to take care of it just like ourselves. My father is good at maintaining vehicles so he is my adviser when I hear something different with my Civic.

I wonder what the most extreme level of car care out there that exists. Maybe daily tune ups and oil changes? Is there any downside to overmaintenance other than perhaps the cost (which I'm not worried about)

The most extreme level of car care would be what I mentioned plus every kind of modification you could think of, both body and mechanical, for the sake of it. I see so many people doing so many unnecessary modifications and adjustments to their vehicles.

Wow. You are caring your car so much. It is better to do these jobs by a professional mechanic. I don't touch the mechanic side of my car.