Well something is definitely
Well something is definitely not right, but there are some ways that explain part of the discrepancy. One is the gears, because most dyno tests are done in 4th gear because it is 1:1 ratio, also as you mentioned the mid-engined designs have lower power loss from the transmission. Next is the fact that certain dynos simply report higher power numbers, like the Mustang dynos. Next is the ringer effect where sometimes the test cars given to magazines are tuned to make more power so the test numbers are favorable. But this sometimes backfires when owners of production cars get lower dyno testing and performance results, which came back to Ford a couple times in the past when their production models made less power than press cars. As you mentioned, the 1/4 mile times say a lot about how much power the cars is actually putting out. The 1/4 mile time is a combination of HP, traction, and shift speed. So an AWD car can have a quicker 1/4 mile time, but usually the extra driveline losses will show a slower trap speed. The trap speed is a great indicator of how much power the car is making. So considering the Corvette's mid engine design, grippy tires, and super quick shifting transmission, it is believable to have a quick 11.2 1/4 mile time, but even with minimal driveline losses it should trap between 125-128MPH with 558HP at the wheels. So the numbers are off, but this was just one magazine test. We are certain to see many more dyno tests of the C8 Stingray before long, and figure out what kind of power the car makes in real life. At least it didn't dyno low, or run slower than the initial acceleration estimates, so it's good news so far.