I also drive a gas guzzling SUV. It's old, however, I made a (flaky) decision to justify keeping it... now that I have one child left at home, I won't buy another big car, this is a kind of SUV swansong for me. So I did a bit of maths and decided that if I made a point of driving it half as often, or even less, then that is like driving a car with twice the fuel efficiency. (Which still isn't great, but better). And since someone else would buy my car anyhow, and perhaps not think that way, then perhaps that is the best thing for that particular vehicle in reducing it's contribution to pollution.
I wonder if that thinking stacks up? Or do I just want my car! Surely in a place like Singapore, you couldn't be doing that many km?