Storage of information in arduino

Im working with a computer for my car.
It have a 3,2" TFT screen wich shows speed, gps coordinates, wvo control, and info about when next service is etc.
I want to have the ability to store the km-info about service in a way that I can change the info without uploading new scetch.
Im thinking maybe SC-card, but that require a SD-card reader for my arduino. Maybe I can use EEprom an easy way?
And I want to control settings with ONE button only.
When setting wvo, I use only one button in a way that U can click it, or hold it for 2sec to use two different functions.

Anyone can help me how to do this most easily?

Using a Arduino Mega

That's just about accessing the on-board eeprom (of which I was totally unaware.)