So far this year, here's what it has cost to keep my 2 Contours running:
96SE = $0.089/mile ($85; nothing but gas so far this year)
98SE = $0.376/mile ($302; bulbs, K&N, CD/MP3 Player and gas)
Yes, I keep track of every vehicle-related purchase.
If it wasn't for modifications, the maintenance costs would actually be pretty small. I tend to do a lot of preventative maintenance and upgrades -- those add up fast. Last year I spent over $2100 on the 98SE (MSDS headers, SVT springs, SVT struts, Mondeo pads/rotors, etc.). I spent less than $900 on my 96SE, but the majority of that was gas, oil and vehicle registration.
I don't mind the maintenance/upgrade costs. I figure a new vehicle would cost me $300/month, so I'm coming out ahead!
