except the fuel bill at the end of the month....
Here (In Italy) you have to pay a property car tax based on the engine power, i believe the property tax for a car like that Bmw 550i must be over 1100 euros/year, i guess both fuel and tax costs won't matter to anyone who owns such thing but having to pay another useless tax it's annoying.
With that age, would it be out of the question to see about doing the repairs yourself? You could probably count on 1/3 the cost of the mechanic's estimate to get the job done right yourself. Just a thought. Head gaskets do suck.
My vote, without knowing anything particular about those specific vehicles, would be the Toyota. I like the Japanese & German made stuff. Sure, Suzuki is Japanese (owned by Volkswagen oddly enough) but I've always seen them as a low-end line.
I don't have neither the tools and experience. And the car already has 162.000km so it's not like the engine is brand new. It might still run some more tough, once fixed (actually, looks like i have a couple friends which might buy it).
I like Toyota's a lot too. Remember the famous TopGear "attempt" to destroy an HiLux?