How much does it cost to rent a one year old Honda Civic with
automatic transmission for 6 months, not counting insurance?

I'm sorry you got no answer. In the USA rentals for 6 months are
rarely offered, and are too costly if you can find one. You may be
able to arrange a 6 month lease on a 2002 Honda Civic if you ask
enough leasing managers. Leasing contracts are tricky, rarely a good
deal, and generally not available unless you are judged a good credit
risk.
 Why not buy the car from a private party, and sell it for what you
can get when you don't need it any more. On the average this is the
cheapest way. Often a credit union or bank will preapprove the loan
before you find the car you want. You probably should forget to
mention that you only want the car for 6 months. Some used car dealers
will sell to you with very little down payment even if your credit is
bad.   Neil