I have read the gas mileage pdf. I'm wondering why my 2010 Prius has dropped about 5 mph over the past 2-3 years. Some of this may be due to more short trips however long highway trips are also about 5mpg lower than in the past when I got over 50 mpg (currently getting about 45 mpg on the highway, 40 in town). These mpg numbers are taken from the read out on the dash. Here's more info: 2010 Prius 3 with 122,000 miles. Bought it 10 years ago when it had 40k miles. I have changed the oil with 0w-20 full synthetic every 5k miles. Changed trans fluid at 97,000 mi. Last replaced air filter at 120,000mi. All other fluids are original (I plan to change them this Spring). Spark plugs are original (need changed). Replaced brake pads and rotors and bled brake lines several times; there are no dragging brakes. Replaced a rear wheel hub 4 months ago. I run Costco top tier gas 90 percent of the time (87 octane). I did a DrPrius test of the traction battery today and it came out as 'good' at 83.5%. I replaced the 12v battery 2 years ago. It has never had a check engine light or error code. Car seems to run perfectly as it always has. Acceleration is strong, no bogging or hesitation. Since the traction battery is okay, I'm wondering the the most likely culprit is the EGR valve, which has never been cleaned. Please let me know what you think. Thanks.
Not sure that it'd be the "culprit" for mpg drop, but definitely get on cleaning EGR ASAP. Any recent tire replacement?
