I have an '06 FEH with 65k miles that typically gets about 30mpg in mixed driving. Last year when my state switched for E10 my mileage dropped to about 28mpg. Recently I've been averaging closer to 24mpg which seems really low.

Is there something that would cause that? Other than oil/filter changes I've not had any maintenance done.

Thanks

 

There are a number of things that have a history of dropping MPG in the FEH.

1. New tires or change of tire brand.

2. Colder weather.

3. Waxing.

4. Tire pressure drop.

5. No electric motor assist.

6. Less EV.

7. 12V battery going bad and more HV battery being used to keep it charged.

8. Quality of fuel.

9. Snow and rain.

10. Higher winds.

Just to name a few.

GaryG

 

sorry newb here so im sure this is a newb question... but wax will hinder my mpg's? i do remember the myth buster episode with the divits on the car but wax would be that significant?

 

Thanks. I did get new tires six months ago but didn't see a drop in fuel economy. It is colder weather, but 24mpg seems awfully low. The EV system seems to be working ok, how would I diagnose? The 12V battery was replaced last year. No wind, I haven't waxed the system and I keep the tire pressure around 40psi.

Would fuel filter or fuel injectors be to blame?

 

If the EV system seems to be okay, it most likely is. Colder weather plus new tires could be the problem. Shorter trips was one I forgot and a route change with more stops can hurt MPG. The fuel filter could be very dirty and effect fuel quality. The fuel injectors in the FEH are self cleaning so you may want to just change the filter. There is a good thread written in this forum on how to change it.

Paul, after waxing my FEH I've always seen a small decrease in MPG. I went from 57.5mpg down to 54mpg and as the car got dirtier again, my MPG tanks got better. I've never seen an increase in MPG by washing or waxing my FEH's. In Sirfergy's case, it could be a combination of things lowing his MPG. If he was getting 28mpg and dropped to 24mpg, waxing alone would not be the cause.

A high oil fill is something to check because that can not only decrease MPG, but it can damage the engine.

GaryG

 

My 2005 AWD dropped from 29mpg (E10) to 27mpg (E10). Temps around here are still in the lower 50ies. I think the drop is mainly due to the winter mix in the gasoline. If you live in a colder place, you will see an additional drop.

 

The waxing statement and loss of mpg is only advanced by GaryG. There is no scientific proof such cause and effect exists.

It should also be mentioned GaryG himself announced a loss of 15mpg when the temperature dropped to 35F in his area in 2010. How much more would the mpg drop if the temperature hit 10F or lower as it did here today?

This is not a flame against GaryG.

 

Billy, do you have a link where I posted a loss of 15mpg at 35F in 2010? There is no 15mpg drop in my mileage log ever. Could it be your taking my post out of context and it was only during the warm-up period and temporary until the battery and engine warmed-up?

BTW, there was someone who confirmed my post here on GH regarding he got better MPG with a dirty vehicle. Looking forward to a link where I lost 15mpg as a average that you are implying. Sirfergy post is regarding a drop in his average MPG.

GaryG

 

Personal statements/experiences are not scientific proof as the "cause of"...

As for the 15mpg loss link, I will find it and post it.

 

I was also going to suggest seasonal fuel changes.

You're lucky. Saturday here is supposed to have a low of -20 to -25°F and a high of -10°F for Sunday.