Modmike is incorrect.
I had no problem getting my imported car serviced under warranty in Buffalo. I never tried bringing it to a Canadian dealer. But now that the warranty has expired (too many miles) I have had no problem buying parts from a Canadian dealer to be installed by my local garage.
No dealer can "delete the warranty". If the dealer refuses to honour the warranty, go to a different dealer. I never had a problem getting warranty work done, and I don't know anyone else who had a problem either.
We saved about $11,000 by importing our car. My next car will be imported too.