One of the first things I do after I buy a vehicle is buy a small spiral-bound notebook (spiral-bound because a pen or pencil fits nicely in the binding.) On the cover I write the make/model/year of the vehicle. In the notebook will go information about all service and maintenance work done to the vehicle from that day forward, with date and mileage noted.

Keep such a log yourself and you'll be able to tell, at a glance, when the oil was last changed, when the brakes were serviced, the struts replaced and the transmission fluid and filter changed out.

This is helpful for both the home mechanic as well as the person who leaves it all to the dealer. While most dealerships do keep records of the work done to your vehicle, having a back-up can be handy. Dealer records do get lost. If you move to another state or use a different dealer/shop, that dealer's not going to have your car in its system. Or, if there's a dispute over a repair with your current dealer, you'll have your records to fall back on.

This can be particularly helpful if a warranty-related problem develops because it may be necessary to produce proof that certain service work - for example, oil/filter changes at the manufacturer-specified intervals - was in fact done according to the manufacturer's recommended service schedule. The "fine print" in some warranties allows the manufacturer/dealer to avoid paying for numerous otherwise warranty covered repairs if the owner can't prove the car was maintained per recommendations.

Your Maintenance Log will allow you to quickly reference the information you need and you should always back that up with your receipts for things like oil and filter changes. Keep that stuff as long as the vehicle remains under warranty. You can staple receipts to pages in the notebook. Or, store them separately, in a file cabinet or folder someplace in your home. Just be sure you do have them somewhere.

The Log is also a good place to keep track of things you might otherwise lose track of - such as that the tires should be rotated this fall or that the battery's getting old and maybe should be replaced before it gets cold this winter. You can jot down a reminder to yourself on a "reminders" page.

Another advantage of the Maintenance Log will show up at re-sale time. Being able to document the service history of the vehicle can be a be very strong selling point that will help you negotiate the best possible deal for yourself.

Even if your trade-in, being able to show that the vehicle was meticulously taken care of should help you wrangle the best-possible trade-in.

You can also use a PDA or similar electronic device to keep a Car Log, but I prefer the old-fashioned notepad because it's simpler, cheaper - and virtually foolproof. It won't crash and can't be attacked by a virus. It's not hurt by heat (as in a glovebox) and even if it gets wet, you'll probably still be able to use it after it dries out. If you get grease on it, it's not going to hurt anything. Etc.

Having a pad and something to write on it with can also be very helpful if you need to leave a note for someone, such as the owner of another car you accidently bumped into in the parking lot. You are going to leave him a note - right?