I have a HCH II with 10k miles. For the first 7k or so I used to average 60-62mpg per tank, 70+ on the way to work, 60+ on the way home. Noticed the last few tanks that I've been struggling to get 58 per tank, 65ish on the to work trip and 50 on the way home. I have done nothing different regarding driving stle/habits. Any input? Can't figure it out! THANKS!

 

First of all: your mileage has been exceptional so you must be keeping your speed moderate and making good use of your hybrid's features.

Some thoughts:

1. How much cooler is it now than when you were getting 65 mpg?
2. Is it more windy than before?
3. I assume you're checking your tire pressure regularly.
4. Have you changed the oil and are you sure it's still the 0W-20 specified? Dealers will sometimes use the 5W-20 common to other Hondas and lube services may even use 5W-30 if they're not being careful.

I have also noticed a drop in my own mileage over the past 2 months. I mostly blame the cooler weather which now averages in the mid-40s most days in my area.

Cheers,

Roger

 

Colder weather? And those are great fe numbers! H

 

Thanks for the insight fellas, it is cooler now. I noticed that over the summer months here in AZ I was getting great MPG, but now that fall is upon us, the temperature has dropped. Guess there is something to the weather effecting the engine/MPG/etc.
I did change the oil recently, got the oil/filter/washer from Honda directly and did it myself. Didn't want any dopes messing with it.
Check my tire pressure every weekend, always kept at 40psi.
I was thinking about replacing the air filter, haven't looked at it yet, but I do live on a short dirt road, could be choking it already....

 

Yeah, I notice a 20% decline (55mpg to 45mpg) during the winter months, although it gets a lot colder here than it does in Arizona. I just put on a grill blocker to try to keep some of the heat in, although I'm not sure if that would be worth it for your temps.

 

I have 64k miles on my HCH II and certainly have observed the big impact of cold New England winters. From April to early November I can keep tanks above 50 mpg (best tank was 56.3 mpg in August only using AC when coasting downhill). In the winter I work hard to achieve 47 mpg. I've posted a number of questions over the past couple of years seeking ways to avoid the winter impact but found no complete solution. My best advice is to allow the engine to warm up as quickly as possible (I try to get up to 40 miles an hour from any stop using 50% battery assist but not more) and minimize use of the cabin heater until excess heat is available. I don't know how much of the root cause is the engine getting up to temperature (it continues to run at red lights when not yet warm) and how much is the change in ethanol mixture (which has less energy per gallon).

 

10% Ethanol in your gasoline could be hurting your mileage. Some states switch over to an Ethanol mix in the winter. Many states are now requiring it year round. It's been horrible on boat engines here in Florida. Clogs up the fuel systems. Avoid it if you can.

 

Same deal here, in upstate NY.. My average normally is 46-48, until late October, and now it's a struggle to get above 40. Asked the dealer and got the same answer- snow tires, wet/snowy roads, winter fuel mix and overall lower temperatures..

 

I'll keep linking this chart of my mpg versus temperature. Pictures are so helpful in these sorts of threads

 

The graph is great - thanks!