Would like to give a few pointers. Hope these helps so you can enjoy your ownership. I'm an owner of multiple big Citroens. Currently still driving one on daily basis.

SUMMARY : In short, I would say treat a Citroen like a French girl. They have attitudes and their own requirements. They are proper continental cars, cheap to buy expensive to maintain. They're not for everyone. But if you love designs and novelty, and you can feed them properly, they will return your love, in a big way. If this is your first continental car, I would advise against buying a Citroen. Also, if you care about Resell Value, stop reading now. Citroen isn't for you.

1. Prepare to deal with spare parts down time. Do not believe in stockist or Naza warehouse. Major spare parts are mostly directly brought in from France upon placing orders. Place orders earlier when there are symptoms (usually technician will inform during service intervals), do not drag until last minute. Expect 1~3 months down time for major issue. Personally I had experienced 6 months down time after accident. DS5 is introduced worldwide back in 2011, expect even lesser support starting from 2021.

2. My current daily run on a THP engine, with full Naza service record. You can send to outside foreman but do at your own risk. First issue is extremely hard to find a someone that specialised in new Citroens. Especially newer and bigger Citroens are designed to be quirky and odd inside and outside. Secondly, you're losing your warranties. There are a standard 5 years warranty and extra 2 years warranty. The latter only covers your engine and drivetrain, but Naza / Brooklands service record is one of the requirement.

3. Why is the extra 2 years warranty important? Because to replace the turbo + peripherals alone will cost you RM12k. Rocker arm cover and engine mountings around RM3k+. Be realistic. THP stand for Turbo High Pressure, and it's the pioneer of downsizing + turbo decade ago. You're bound to face this, it's normal. Peugeots and Minis with EP6 Prince engines suffer the same too. Don't compare to a Japanese or naturally aspirated car.

4. The worst of luck is climate control system failure. The cost is from RM2k(cooling coil) to RM15k (evaporator housings and their reduction gears) worst case. I personally do not see this as big issue also because I had same experiences with Mercedes, BMW and Volvo (Yes, don't believe that German cars are bullet proof). One thing I learn though, is never let the climate control work in 'auto' mode. Manually set your temperature and fan speed for all 4 zones. That could prolong the life span.

5. Normal service cost is on par with, if not slightly cheaper than Germans. Key costs include 5.5L of Mobil 1 @ RM70+ per L, brake pads @ RM400+ per pairs, brake disc @ RM500+ per pairs, Naza pricing. I drive my daily fast and hard like a hooligan (yes, I'm not joking), service costs are around RM700+, RM2k+, RM700+, RM2k+...10k km or 3 months interval. Expect lesser for your part if you're a tame driver. I would advise against using Petronas Syntium, the engine feels reluctant to work under Malaysian hot afternoon sun.

6. Maintain your car on strict basis, or even more frequent than what is recommended. THP beefiness and French car hard braking is sweet only when it runs on optimal conditions. You'll hate driving your car if it's not properly maintained. In the event of accident, minor or major, tow back to Sungai Besi Citroen service centre. They do body and painting, and they claimed from insurance.

7. For fuel, RON97 is recommended. RON95 can be used but the engine run very coarse. The difference is very obvious.

(P/S : Sorry for the length. As an owner, I feel sick reading or hearing non owners bashing the marque based on hearsay. Citroens deserve justice.)

Bro Hey_Dexx
DS5 is a lovely car,if you like it go for it. I'll point out some details you should know. 2 engine options were brought to Malaysia - 1.6thp & 2.2turbo diesel. I did quite a bit of research on 1.6thp Prince engine, found some valuable info. 

Early Prince engines has a few issues. The engine has gone through a complete make over in 2012(code:EP6CDTM) which has made it reliable, most of the early issues were solved. As a result PSA offered this, as one of its engine option on Sedan/hatchback/SUV/MPV vehicles as 2014, on both Citroens & Peugeots.

Prince has gone through further refinement which is now fitted to facelift models. Since you are looking at a used one, go for the EP6CDTM engine.

EP6CDTM  carried the following mods:
1) Engine tuned to run on RON 87 petrol
2) Remapped ECU
3) New designed piston with lower compression
4) New designed catalyzer.
5) New engine oil filter housing with heat exchanger
6) New turbo charger
7) New fuel tank gauge unit with lower pressure pump to handle lower grade petrol.
8) A fuel filter to cater for hash atmospheric condition ( third world country)

I'm glad to say mine is 6 years now and running without any issues! Fortunately there are now Citroen/Peugeot specialist workshops in Klang valley. I can testify these guys do a better job than most authorised SC. I dare say your car can be maintained in top condition by these workshops! Here are their contacts for your use.