Hmmm, an apology first: it seems iOS disapproved of my word 'snicky' for the Toyota gearchange and, er, snicked it out.
As for character, I agree, it can be too much of a good thing, just as that 'character' who's such fun in the pub once in a while would drive you mad over breakfast every day. I think a car needs a base of competence, to make bearable the journeys you have to do, and, ideally, a dose of charm to make those journeys pleasant and to turn the journeys you do for pleasure into a real occasion.
Our Toyota had the competence - it's what Toyotas do - but that was where it ended. It crystallized for me on a beautiful July day last year, driving back through mid-Wales and Shropshire after a soggy week in Snowdonia. It should have been perfect but it was merely OK. Charm, I'd say, is presenting yourself in a way another person can find appealing or enjoyable, and requires a degree of empathy; a car can't have that empathy, of course, but a designer can. My old Volvo shows this everywhere, and the Mercedes' design is growing on me too. The Toyota never had it and that, as Sirallun might say, is why it had to go.