FAQs

How do I increase gas mileage to save money?

Drive Sensibly

  • Aggressive driving such as speeding, rapid acceleration and braking can lower gas mileage by 33% at highway speeds and 5% at town speeds.
  • Fuel Economy Benefit 5%-33%.
  • Equivalent Gasoline Savings: $0.18 - $1.20/gallon.

Observe the Speed Limit

  • Gas mileage usually decreases rapidly at speeds over 60 mpg. Assume that each 5 mph over 60 mph is like paying for an extra $0.29 per gallon of gas.
  • Fuel Economy Benefit: 7%-23%.
  • Equivalent Gasoline Savings: $0.26-$0.84/gallon.

Remove Excess Weight

  • An extra 100 pounds in your vehicle could reduce your MPG by up to 2%.
  • The reduction is based on the percentage of extra weight relative to the vehicle's weight and affects smaller vehicles more than larger vehicles.
  • Fuel Economy Benefit: 1%-2%/100 pounds of weight.
  • Equivalent Gasoline Savings: $.04-$0.07/gallon.

Avoid Excessive Idling

  • Idling can use a quarter to a half gallon of fuel per hour, depending on engine size and air conditioner use.
  • Fuel Cost Savings: $0.01-$0.03/minute with the air conditioning off.
  • $0.02-$0.04/minute with the air conditioning on.

*Cost savings are based on an assumed fuel price of $3.65/gallon.


Which motor oil and which filter is best for my car?

  • For the motor oil use the manufacturer's recommended grade of oil. Also, look for motor oil that says "Energy Conserving" on the API performance symbol to make sure it contains friction reducing additives.
  • There are many different makes of air filters. Make sure it is the right size and the air filter is clean and carefully installed. We will gladly search for the right size filter and make sure that the installation will be successful.

*Any OEM part we replace will be of equal quality.


Will my car perform better if I put higher grade octane in?

  • This is a common misconception, the answer is no, each type of car is given a recommended octane level which resides within your owner manual, other octane levels will not perform any better and may actually cause damage to the emissions system.
  • A helpful tip, check the octane rating on the yellow sticker on the gas pump rather than relying on descriptive labels because different gas stations regular, mid-grade, and premium octane levels may vary widely.

What do these warning lights mean?

Maintenance Light Service Light

"Service Engine Light" or "Maint Reqd" light

  • This light merely tells you that an upcoming service may be required and to check with your mechanic.
  • The "Maint Reqd" light is in a specific spot in the photo below, please note yours may not be in the same location.
Maintenance Light

Electrical Fault Light

  • Normally looks like a battery but can look different in any car.
  • This light will go on and turn off when you start your car as a self test.
  • If it stays on that means your alternator or its belt is faulty and needs to be replaced.
Brake Light

Brake Warning Light 1

  • This light has a different use depending on the manufacturer, it can mean your parking brake is on or that a fluid is low. Consult your handbook and if required consult a technician.
ABS Light

Brake Warning Light 2

  • Only in ABS (anti-lock braking system) equipped cars.
  • Will turn on and off when the car is started to self-check-If it flashes, throbs, or stays on, if it does anything to get your attention, get this checked out ASAP because the ABS computer has found an error.
 Schedule Service  Contact  Service Deals
Service 703-385-0500
Parts 703-385-0500
Collision Center 703-385-0500
Monday 7:00AM - 6:00PM
Tuesday 7:00AM - 6:00PM
Wednesday 7:00AM - 6:00PM
Thursday 7:00AM - 6:00PM
Friday 7:00AM - 6:00PM
Saturday 7:00AM - 4:00PM
Sunday Closed
Monday 9:00AM - 9:00PM
Tuesday 9:00AM - 9:00PM
Wednesday 9:00AM - 9:00PM
Thursday 9:00AM - 9:00PM
Friday 9:00AM - 9:00PM
Saturday 9:00AM - 8:00PM
Sunday 12:00PM - 5:00PM
Monday 8:00AM - 6:00PM
Tuesday 8:00AM - 6:00PM
Wednesday 8:00AM - 6:00PM
Thursday 8:00AM - 6:00PM
Friday 8:00AM - 6:00PM
Saturday 8:00AM - 4:00PM
Sunday Closed
Map of DARCARS Pre-Owned Fairfax in Fairfax VA