my japanese ones do.

Yes, Should turn a nice colour before it does.

The non-Japanese ones shed their leaves as well. Nice colour depends on the climate where you are. Our trees leaves just go brown and fall off - even the Japanese ones. It's too temperate here for good colour changes.

The only Acer that is hardy and evergreen is the Cretan Maple (Acer sempervirens). It has small, leathery lobed leaves. All other hardy types lose their leaves in autumn.