I own both the mazda 3 speed and the civic RS turbo. For fuel economy and fun to drive, agility I'd go for the mz3. For interior space it would still be the civic specially the rear legroom noted that the mz3 is a tad smaller but anyone 5'7 or 5'8 will have no trouble at the rear of the mz3 unless you're terribly horizontally challenged. Since you're comparing the mid spec version the civic 1.8e is the old engine from a decade ago.