Salaam ,
The fuel consumption of 1.3L Rotary is 5 to 6 Km average , max 10 km if you drive her like granny .
It is absolutely better to own a RX-8 with a Rotary engine .
Rotary engine stops functioning properly after 30k kms ? you give me a Rotary engine (at your cost) and i will make it dis functional at just 5k kms 
who ever told you this story does not how to maintain a Rotary engine or probably never owned one .
The key for a long lasting and a healthy Rotary engine lye in religious maintenance , you take care of the engine and it will serve you years and years of loyal service 
TIPS ABOUT KEEPING YOUR RX-8 and RX-7 (ROTARY ENGINE HAPPY)
- always put Hi-Octane fuel
- let you car warm up first before driving
- never shut off your rotary engine when it is cold , it will cause engine flood
- use only non-synthetic oil for your car
- change engine oil at 2500km or 3000km (i change it at 1500km for my RX-7)
- always change oil filter when when changing engine oil
- always top up your engine oil when you refuel your car (rotary=oil burn)
- let the car rest for a while (2mins) before switching off the engine
- rotary engines are rev happy by default
10.red line your engine occasionally , rotary engine enjoys to be red lined
Fahd.