1. What is the average FC?
This is subjective depending whether its city, highway or town driving, as well as what modifications has been done.
What i got is by average 12-14km/l. Some vios that went long distance can easily clocked 15km/l - 17km/l++.

2. Mileage per tank?
Same as above, its depending to various factors. I believe by average when the last bar is blinking (Vios uses 8 digital bars for fuel tank reading, similiarly like the myvi/viva), you can easily clock 450-500km++.

3. Can it run on RON95?
Yes as the minimum RON required for the engine is RON 91 as tested by Toyota.

4. What are the service intervals for the vios?
For the 1st 10k km, u may need to perform mandatory service by 1k km, 5k km and 10k km. But once after u completed ur 10k km service, u can choose either to service every 5k km or 10k km. For 10k km service its advisable to use full synthetic engine oil while for 5k km service is compulsory for those wanted to use mineral oil.

Official service intervals as per UMWT recommendation
- Every 30,000km aircond service
- Every 40,000km major service (mainly other fluid change)
- Every 80,000km super major service (major + throttle body clean)
- Every 100,000km tube/hose replacement (also coolant & spark plug)

Engine Oil specifications by UMWT service, using Penzoil
- Mineral Oil 20w-50 (change every 5k)
- Semi Synthetic 10w-30 (change every 5k)
- Full Snythetic SW-40 (change every 10k)

5. How long is the car's manufacturer warranty?
Standard 3 years or 100,000 km or whichever comes 1st. Does not covers wear n tear parts like brake pads, tyres.

6. Can i change to aftermarket parts
Yes u can, but once if u bring back to Toyota servicing and the fault was caused by the aftermarket part, ur part warranty is void for sure.
Say i change my stock springs to aftermarket springs and then i returned to toyota to complain the absorbers were faulty. Since it is possiblity caused by that aftermarket springs which is not from Toyota itself, the car's suspension system is completely void of warranty.

7. Can i service outside when i still on warranty period?
Advisable not to do so as this will indefinitely void ur car's warranty.