How is the fuel economy of the RX8?

I'm thinking of getting an RX8. Which model should I buy?

When the engine is idling, the RPM is stable at around 800. However, when you press the clutch and shift gears, the RPM increases to 1200 (without releasing the clutch, just purely shifting gears). What could be the reason for this? (The transmission, clutch, and flywheel have been checked and there are no abnormalities.) Car model: Manual rear-wheel drive Mazda 6-speed manual RX-8 Type S.

Does the rotary engine of the RX-8 need an overhaul every 10 km?

How to replace spark plugs on a Mazda RX-8? Where are the spark plugs located?