It's not that straight forward, and I think you can only tell what you'll do when it's your turn to do it.
We could have afforded the M5 rather than the M550d, but a car's payment is something that we're agreeing to, and that's something we can control and are prepared to do. However fuel prices are insane, specially petrol. And each time you fill up the tank, even with the diesel, since we can't go under 11.0L/100km, It's a big ammount of money we're spending, and we have to fill up the tank every week, and it's not driven too much. Each month we spend around 250€ in fuel. That's 3000 per year. Then you also have the insurance which is not cheap.
The M5 would turn out much more expensive on the run, expecting around 320-350€ of fuel per month. With 300 per month you can buy a small car lol.
When you buy a car you can't just account what you're paying when you get the keys.
Also due to the price cathegory of our car we pay an extra 20% of fuel price, so on top of the 3000€ of fuel per year we pay another 20% of that.
And for which reason would we get the M5 instead? None, we don't race, we don't track the cars. My father only stretches it when the roads are empty at night or in highway driving, most of the days he's under 50-60km/h. I already think that our car is to powerful for what we can do on our roads.
We've already been in situations in which we think, I'd do this and that if I were going to do X instead of doing what someone did, but when it's your
turn to decide on the very same thing you'll think it over better^^
Just saying, things are not that straight forward xD