15K, hmmm u can get tons of options like a used iswara from 2000 and above. Or a wira from 94 onwards, but dont expect loan available.
Why specificity an Isuzu? Toyotas are popular in East Malaysia, why not find a toyota landcruiser instead?
Hmmm i would prefer the honda jazz cause the car can last for long. But since u not planning to change for many years to come, the Hyundai Matrix will be a better bargain.
50K for a 1 year car? Nego it to 48k. I personally dont recommend taking 9 years, and best is ur car loan must not be more than 1/4 of ur salary, although the bank requirements is max 1/3 of ur monthly salary. Hence i prefer u to take 600 per month commitment. Used local car, hmm, be prepare for interest rate around 4%.

I hope u find the loan calculator useful here. http://autoworld.com.my/v2/tools/loan_payment.asp