So in your first post you said you wanted a Civic then now a smaller car.
I'm confused.
I don't know if they still have any cars after doing the stock clearance but you can check this out.
2009 Toyota Altis 1.8 - don't muck about it get a good car like the Altis, it has the safety features that would give you peace of mind when travelling on the highway everyday, being a 1800cc car you won't feel tired driving an under powered car and having to push it to it's limits everday, maintenance wise i wouldn't say it is cheap because it is a C-segment afterall so expect normal service around RM120-170.
I'm going to assume you'll be paying a cash amount without any loan attachment.
Also do note that most of the prices quoted when used car dealers sell the car is the car price, even if he absorb the GST, you'll still have to top-up roughly 2-3k for runner handling charges, jpj inspection, roadtax and insurance.

You're in luck since I am also searching for a "cheap shit" car that can be capable of highway usage. My requirements is basically to find a car that is cheap to buy and maintain while mostly being a in town runabout but capable of highway journey's from Johor to KL, and it must be comfortable as my group coming up and down KL is usually 4 adults.

2006 Nissan Latio 1.6 Sedan - usually even this old it is above 20k but the owner is doing a quick fire sale at 15k, you might wanna give a call to check it out, if it is legit then it is a steal. It should be able to fit all your requirements. While still being slightly newer than your target of 2005 cars. You can read more about Latio's in my previous posts.

2004 Toyota Altis 1.6 - checking around there aren't any 2005 models within your budget and for 2004 only a handful of cars available (in KL region), anyway this particular ad the car looks in relatively good condition plus it is stock so hopefully it was well taken care of and driven by a lady to go pasar buy vege only. All in all, when going for older cars if you do not know what you're doing or much about maintenance then it is better to go for Toyota's as they're cheaper to fix it anything goes wrong and are built quite tough so even if it wasn't serviced well it should still be okay.

If you're willing to up your budget there are better cars you can choose;

2006 Mitsubishi Lancer 1.6 - there used to be many for sale but nowadays few remaining and there is reason too as now is 2016 and the last batch of these cars that were sold were in 2006 so this is the last year someone can actually buy them using loan. It is a relatively good car as it shares much in common with Proton Waja as they come from the same platform so there are parts that can be shared between the two so you can source for cheap parts via this avenue but if you can't then you can always still get new parts from Mitsubishi Malaysia but it would cost you