Ever wondered why?
No.
Only double of an MCR 4S.
You're comparing a certified production airplane with an experimental homebuilt?
The MCR4S advertises 20 litres/hr for fuel burn (five gallons an hour), while the 172 does about six to eight gallons per hour. Not really double, is it?
The MCR 4S advertises 236 kph at 8,000', which is 146 mph, which is 127 knots. The 172 averages around 110 knots. It hauls about the same load. It goes about the same speed. It burns about the same amount of fuel.
Of course, you can buy the 172 for less than it will cost you to build the MCR, and you have a proven airframe with parts availability, a well established mechanical history, which is not experimental, and which you don't have to build.
The MC-whatever runs about sixty four thousand euros for a kit, and that doesn't include engine, propeller, avionics, instrumentation, wiring, etc. A working, running, certified and operating 172 can be purchased for less than the MC-whatever's raw parts and materials. Not a bad deal, considering that purchasing the 172 means one gets to fly home, rather than take a crate home that might one day, years later, become an airplane.