Back when we first purchased our 2008 Honda Pilot EX, I was thrilled with the fuel economy. On our initial trip from Nashville to Atlanta and back, I consistently achieved 23.9 mpg. I made a conscious effort to maintain a speed of 70 mph, only briefly increasing to 75 mph when going downhill. Subsequently, a tank of gas used mainly for city driving by my wife still yielded a respectable 20.0 mpg. So far, so good!
However, our optimism waned after an October trip from Nashville to Huntsville and back, which resulted in a disappointing 18.5 mpg. I maintained the same driving style as before, leading me to suspect something might be amiss with our vehicle. Could the engine control unit (ECU) be running a richer fuel mixture than necessary? It was puzzling.
Our most recent 270-mile journey, consisting of 80% driving at 60-65 mph on state roads and 20% at 70 mph, further fueled my concerns. Despite my best efforts to drive economically, the trip only returned 21 mpg. This was achieved with no air conditioning, two adults, a ten-year-old child, a dog, no additional cargo, and tire pressure set at 35 psi all around. While the tire pressure was slightly above the recommended highway rating, I still anticipated fuel economy closer to the initial 23.9 mpg, especially given the lower average speed compared to our first trip. Even employing fuel-saving driving techniques, I couldn’t surpass 21 mpg.
The stark contrast in fuel economy between when the Pilot was new and now is hard to ignore and seems unlikely to be solely attributed to driving style variations. It makes me wonder if the ECU is now operating with a richer fuel mixture than it should. This could potentially be due to an overly sensitive knock sensor or malfunctioning sensors like the oxygen (O2) sensor or other related components. I understand that diagnostic codes might not always be triggered, as sensor readings operate within acceptable ranges, but these ranges might not be optimal for fuel efficiency.
What’s particularly striking is that achieving 23.9 mpg on the highway seemed easily attainable when our Pilot was new. Now, with 5000 miles on the odometer, 21 mpg is the absolute best I can achieve, even at a more fuel-efficient speed of 60-65 mph. This noticeable decrease in Honda Pilot Gas Mileage warrants further investigation to pinpoint the underlying cause and restore the vehicle’s original fuel efficiency.
