Fredphua,
I guess based on the prices from mudah.com, some of the e39 525i (Japan specs) maybe a 523i re-badged as 525i. Both 525i and 523i share the same engine (either M52TU or M54) and the only difference is the hp. Best is to use REALOEM.com and check details with the VIN number.
Have you checked the VIN details of the car?? Is it a M52TU or M54 engine?? If it is a M54 engine, that's the latest engine for e39. M52TU (technical upgrade) is the version prior to M54 and both are double vanos.
1. Steering vibration when brake is usually worn disc rotors. Ask the dealer to replace 2 x front original disc rotor & brake pads.
2. Take the car to ChuSeng and ask for a complete computer scan (check for any error codes) and mechanical checks (suspension - absorbers, upper & lower arms), check for oil leakages (steering rack, oil pan, auto trans, power steering), water cooling system (radiator, expansion tank, all hoses).
3. After check by ChuSeng, ask for an estimate quotation for the repairs.
http://www.mudah.my/BMW+525i+E39+SHIFTRONIC+04-7091830.htm ( RM 79,800 registered in 2004 but don't know year of production)
http://www.mudah.my/BMW+525i+Auto+Shiftronic+Japan+Spec-6048208.htm (RM68,900 registered 2005, production 2000 Japan specs. Again it could be a 523i but re-badged as 525i).
http://www.mudah.my/BMW+525i+E39+FACELIFT+MILE+70K+02+07-7084204.htm (RM91k registered 2002)