Hi,
I'm driving a 12 yr old COE car.
Including monthly instalments, road tax, insurance, petrol,
parking, maintenance and other incidentals, I spend about $1,500
per month on my car.
Of course petrol is a little on the high side ($400-500 per month)
compared to most others ($150-300), and I do spend quite a bit each
year on small upgrades (sound system, tyres, wheels,...).
But it's the unforseen ones, like the changing of clutch assembly,
alternator, radiator, water pump... that starts to accumulate. Not
to mention the occasional "fender bender". 
In the end, despite all the excess spending, I actually have grown
very fond of my car. 