Tex:
Keep in mind that HK is not a fine or a tax city... so 20% should be generous. However, housing can be pretty expensive.
You should be able to get some pretty decent options in areas like Repulse Bay, Stanley, Clearwater bay in the HK$ 60K range.
Take a look at
http://www.centanet.com or
http://www.gohome.com.hk for options in that range.
Parking will be a majority of your car expenses. Try to find an apartment which includes a car park. Parking at work is usually iffy .. depends on where your company is and the arrangements they have for parking with the building they're in. A parking lot in Central can run between $3500-5000/month.