Heated Seats...Every time you turn on an electrical device in a vehicle it has an effect on gas consumption enen though it may be miniscule. The more electricity you use the harder it is to spin the aternator due to an increase in magnetic flux density. I have heard headlights can reduce gas economy by about 1% (if on all the time), but that is only about .25 miles/gallon and the headlights draw a lot of current. Remember the heated seats switch to low after 5 minutes so I doubt you could even measure a difference in MPG.

Hard water / Paint Fading ... It won't fade the paint but could leave a film on it causing it to look faded. If you dry the car after you wash it or use the "Mr Clean Autodry" system it should not concern you. The auto car-wash will do a lot more harm than hard water.

Regards
Rich Magnanti