^ a slow leak in a tire makes you consider the car "unreliable?"
When I have a slow-leak I usually air it up with my (not expensive and not large) air compressor until I have a day off in which I remove the wheel/tire put it in the back of my beater car (it looks as though you own a truck) and have the local tire-shop fix the leak. Usually just a nail, I only took a slow-leak to BMW once. They didn't want to patch anything, just wanted to replace the tire, I thanked them for their time and went home to handle the problem myself.
That "beater" car I speak of, I consider that car unreliable, sometimes it starts at temperatures below 40 degrees, sometimes it doesn't until you crank on it for 10 minutes with your foot to the floor. If you let up on the gas pedal while cranking for +/- 10 minutes and then try to start it again it will back-fire and break the MAF sensor (+/- $45 a pop used). Thats unreliable...
-- '03 330i ZHP