As far as I know the only hummers you probably can see is from
US Military.
Last time they shipped US tonners and Hummers in for an exercise
with Singapore in 2003. Saw them around Bedok Camp area, they still
retain their US plates though.
i won't be surprised if the Sembawang US navy base has a few
hummers, but those will either have USN 1234 or US 1234 AF
plates.
I don't think anyone in their "sane" mind will own a hummer in
singapore with such road tax system.
Plus i doubt they can pass emission standards.
which makes me wonder... how did H2 pass Calfornia emission
standard.