You need to refer to three main websites:
Royal Customs of Malaysia
MITI
MOHR (human resource ministry)
If you are a student, MOHR probably doesnt apply. Within the MOHR website, there is a link to a Program providing incentives to skilled professionals abroad. If you qualify, you get to bring two cars back tax free. Its a lenghthy process and will not be eligible if already back in msia.
Royal customs shows you the sample computation of tax rates etc. Beware that you will have to incorporate import duty, excise tax and sales tax which all adds up to an awful huge amount. Several friends have computed and thought that it wasnt worth the effort considering the ambiquity. Also, you need upfront cash to pay taxes. I heard from some ppl also that there is a one off cap tax of MYR15k on cars older than 8 yrs (cant confirm), this may be an option if you like say an 8yr old boxter or merc which r fairly good cars. You need to ask some serious questions whether you want to bring the car back at all because used imported cars have dropped in price slightly in msia.
You need to understand that taxes are independent of AP permits. You need to read the MITI website for rules on APs for your car. One of them being a requirement of 9 mths ownership prior to shipment back to msia.
This is just a brief summary of the fine prints included in the three websites, nothing beats reading it yourself. Hope this helps!