What should my brother do to care for my car while I live in Japan?

I am moving to Japan for one year. I have a 2003 Subaru Legacy station wagon with 74,000 miles. I bought it used and I owe just under $7,000 on it. I was planning to sell it and pay off the loan and then buy a used car when I came back to the USA. My older brother said that would be a mistake because I would lose money overall by going that route. He offered to store my car in his garage and do whatever to keep it in good condition while I am gone. He is a responsible person and wants to help me out, but he does not know that much about cars. What does he need to do to keep my car in good condition? He has his own car so he will not be routinely driving mine - just doing whatever is needed to keep it in shape. We both live in Maryland (so, winter might be an issue).