after test drive the Merc C250 CGI, make sure u go scout for few units on-the-road and see if u like the lights at night. check it out and u'll know what I mean. it's harder to see the diff during your regular day time short test drive session.
all these cars has it's pros & cons.... so ultimately it's still a tough choice...
1. Merc C250 CGI -'cheapest' & latest design + new Turbo engine, but drive & handling can't really be classified as Sport Saloon even under Sport mode. LCD screen cheapo look compared to i-drive. Sales man will tell you fancy features like Voice Activated GPS, blah blah blah.
2. Audi A4 Quattro - Msia is probably the few countries where u can find an Audi that is more expensive than Merc. but it's a fully imported unit rather than CKD. Design & Handling wise all fulfill ur requirements as 'Sport saloon'. Don't have to worry bout CKD A4 Quattro in the near future as well.
3. 325i - 3 series is at it's last leg now... and that's applicable across the board including the 320d & 335i. expect alot of gimmick for sales push.
no comment on Passat cause I haven't test drive 1 b4... but the design cue is quite similar to the older version of CLS....
I don't suppose you'll include Volvo in your list of selection, but if u have spare time after the Merc test drive session, might be worth the effort to check out the new S80 Turbo. 340 Nm, 0-100 under 7.5 sec. now raya promotion comes with alot of free gift too. all-in price incuding insurance should be still below 300k.
If u don't mind recon car, Naza had thrown out 7 units of Porsche boxster (2005/2006) at around 270k for raya promotion. all snapped up liao last I check them out. not sure if they'll have more of those stocks coming in soon. they still have some 09 E class selling under 265k, but I don't think E class suits your requirements & definition as Sport saloon even though those few units are Avantgarde version.
happy hunting....