I'll partially agree with you on Honda/Toyota reputation as being a contributing factor but guess what? They've EARNED that reputation. I still see plenty of Accords and Camry's from the 90s on roads today 25 years later. How many Mazda 626's from the 90s do you still see running? They're all in scrapyards. And it's not just Accord's and Camrys that also outsell it, but also Kia Optima, VW Passat and Hyndai Sonata as well. Does that mean Hyndai and freaking Kia have a better reputation as well? That's pretty sad if true. And your dad bought a Mazda6 over a Camry and Accord, that's great. There are also people out there that will buy Chrysler over a Toyota for their own reasons, who cares?
And the way the Mazda6 'involves the driver as well as being efficient is a key selling point?' That's funny to use 'selling point' when the car doesn't even sell. I also think it's very telling how no one else here on the forums backs up your argument, likely due to the Mazda6 regularly getting bashed here for it's lack of power by it's own members. Hope your dad enjoys his Mazda6