So I have about 8000 miles on my 2021 advanced and my mileage range after fill up went from about 325 miles when new to about 285 miles now. Can anyone explain the big decrease?

 

Highly dependent on your driving style. Did you change the IDS from Normal/Comfort to Sport since the 325 mile range?

 

There are so many possible reasons for this. Are you driving exactly the same, in the same drive mode with the same traffic, over exactly the same route for multiple tanks and precisely measuring and charting those results? Are you always filling up with the same grade of gas with the same ethanol content, from the same station at the same time of day?

If you’re looking for a mechanical explanation, maybe the “learning” transmission has changed since you bought it, and has adjusted to your spirited driving. Reset the transmission and see if that changes things? But otherwise I’d say it’s most likely that your driving pattern has subtle differences over time that have added up to change your mpg. As they say, you can never drive the same road twice.

 

My mileage has taken a hit as well.
In PA, they use a Summer blend of gas that contains up to 10% ethanol.
Secondly, the a/c compressor runs more in the hot weather.
Third, during the height of the pandemic, there was virtually no traffic. Everyone seems to be back on the road now.

 

If you have a tank that ends up with a higher average MPG, the range will show as higher at the beginning of the next tankful. It looks back on the previous tankful, (maybe two?) to give you a rough idea of the range. This is also dynamically adjusted as you use the gas in the current tank. The range number is always a guess, and is USUALLY optimistic at the beginning, and pessimistic at the end. Meaning when it says 0, you usually have a "few" miles left.

 

We don't keep detailed records so I could be all wet about this but just going by the average mpg on the display, it seems that ours has gone down over the last year also. When we first got the car, combined mpg was about 23-24 and it was pretty easy to see 27-28 on the highway if I remember right. Now at 11,000 miles, combined is 21-22 and we need a good tailwind to see 26 highway. We only use the comfort mode and I don't think our driving habits have changed.

The only thing I can think of is that at the first oil change at 4,000 miles I switched to 5-30 oil instead of the recommended 0-20. I find it hard to believe that that would reduce mpg enough to notice but maybe so.

 

Maybe the tires? Extra weight for sound deadening?

 

Supposedly, there's a way to reset the ECU and transmission so it will re-learn your driving style. I tried it a while back but I couldn't really tell if it did anything.

 

LOL, yes I had forgotten all about the different tires and sound deadening material but I have no idea how much weight that might have added.

 

One thing I have noticed about efficiency on this car. When it was new I drove it easily. I wanted to get the best mileage and such. As time passed I got into enjoying the performance end of it and decided I upgraded from a CR-V to the RDX to have MORE. So while I still drive reasonably most of the time I really don't mind letting her zoom once in awhile..in a good way of course! That does cause the estimated range to drop on the next tank but so what. I got this car for fun and I want my fun!

 

As mentioned it’s an estimate or guess based on recent average MPG.
Range is based on 15 gallons available to give adequate warning witha cushion.

RDX often shows 390 range. 26 x 15

Ridgeline often shows 408 range. 24. X 17 gallons

At 325 mile range it’s thinking your going to get 21.5 MPG.

 

Mine almost every time after fill up tank showing 415-425 miles, and when Low fuel lamp goes on (it means about 35 mile left), distance showing 380-390 miles . Average showing about 27.5 - 27.7 mpg.

 

What type of driving you do?

 

Only off highway, 30 miles trips to work every day..