Just to play devil’s advocate… the AMG C43 is on paper a comparison against the M340i. But in real life, the AMG C43 seems to under-deliver against the M340i (probably due to the 4 banger vs B58, general driving feel, and MBUX vs iDrive).
So, Mercedes seems to be discounting the C43 quite a bit. For someone that just wants a sporty sedan with ICE motor, the AMG C43 could be an option.