Car guides
Short, plain-English guides to the money and upkeep side of owning a car: claiming work miles on your taxes, figuring your real MPG, and knowing when oil, tires, brakes, and other parts are due and what they cost. For your own car, see the maintenance pages by make and model.
Taxes and work miles
- IRS mileage rateThe current rate per mile, past rates, and which one applies to your trip.
- GSA mileage rateThe rate federal employees are paid back for driving their own car.
- How to claim mileage on your taxesWho can deduct work miles and how to figure the deduction.
- Mileage log for taxesWhat the IRS expects your mileage records to show.
- Standard mileage vs actual expensesThe two ways to deduct car costs, and how to compare them.
- Commuting milesWhy the drive to work is not deductible, and the exceptions.
- DoorDash mileageWhat DoorDash reports and which miles you can deduct.
- Gig driver mileageUber, Lyft, and other apps: the miles you can deduct.
- Employee mileage reimbursement rulesWhen reimbursement is tax-free and when it is taxable.
- Mileage reimbursement laws by stateWhich states require employers to pay for work miles.
Gas and MPG
- How to calculate MPGFigure your gas mileage by hand from two fill-ups.
- How to split gas moneyFair ways to share gas costs with friends or coworkers.
- What is good gas mileage?Typical EPA ratings by type of car, and how to judge yours.
- Premium vs regular gasWhat octane does, and when premium is worth it.
- E15 and E85 gasWhich cars can use them, and what they do to MPG.
Oil and maintenance schedules
- Car maintenance scheduleWhat is due and when, by miles or months.
- How often to change oilYour manual and oil life monitor come first.
- Oil change costWhat an oil change costs, and what sets the price.
- Going past an oil changeWhat the oil life percent means and how far you can go.
- How to reset the oil lightThe three common ways to reset it after an oil change.
- Normal vs severe maintenanceWhich schedule fits the way you drive.
- Maintenance by car make and modelSchedules, reminder codes, oil, and tire pressure for popular cars.
Brakes, fluids, and battery
- Brake pad replacementCost, how long pads last, and when to replace them.
- Brake rotorsReplacement cost, minimum thickness, and signs of bad rotors.
- Brake fluid flushHow often to change brake fluid and why it matters.
- Transmission fluid changeHow often, drain and fill vs flush, and CVT fluid.
- Coolant flushCost, how often, and signs of low coolant.
- Differential fluidCost, how often to change it, and signs of trouble.
- How long a car battery lastsAbout 3 to 5 years, and the signs it is failing.
Belts, filters, and spark plugs
- Timing belt replacementCost, interval, and signs of wear.
- Serpentine belt replacementWhat sets the cost, how long it lasts, and signs of wear.
- Spark plug replacementCost, how long plugs last, and signs they are worn.
- Engine air filterWhen to replace it and how to check it.
- Cabin air filterHow often to replace it and how to do it yourself.
Records and warranty
Warning lights
Buying a used car
Tires
- How long do tires last?Tread depth, tire age, and the signs it is time for new tires.
- Tire rotationCost, how often, and rotation patterns.
- Wheel alignmentCost, how often, and signs you need one.
How we write our guides
Each guide gives the plain answer first, then the details. Rules and numbers come from primary sources, such as IRS publications, NHTSA, and owner’s manuals, and each guide lists its sources and the date we checked them. See our data sources. Your owner’s manual, your tax professional, and your employer’s policy always come before a general guide.