Hello everybody.

I drive a 2006 Mercury Mariner Hybrid with about 97,000+ miles on it. I bought it used with just under 12,000 miles on it.

When I first had the car, I routinely got 28+ MPG in the Winter and 31-33 MPG in the summer. This was primarily all on a 50 mile (each way) commute with one toll on a bridge, mostly flat ground.

I changed jobs just over a year ago, and now I have a much more rural drive. There are a lot of hills and no tolls. I now get about 26 MPG in the summer, and 21-23 MPG in the winter.

I notice a slight improvement on these numbers when I do my "old commute," but the gas mileage still isn't what it used to be.

What can account for such a drastic drop in gas mileage? What can be done to improve my gas mileage? I'm good about my tires and stuff.

Any and all help would be appreciated. TIA

 

A general question--why isn't my mileage what it use to be?--could require a dozen or more inquires about specific operations of the vehicle. Examples:
-tires, tires pressure
-fuel composition
-vehicle operation-- rpms?, engine temperature, ...
-weather--temperature, wind,....
-other...
Sorry for this answer but you need to provide some more "details".

 

It is hard to determine without more information.
Change in fuel formula is a biggie.
Least likely, but possible is something mechanical is wrong.

Do you see higher RPM's than usual? Are you driving faster on the average?
It is colder than average?

With good gas, here's how my FWD does with speed:

About town, with lots of stops, but lots of EV time, 20 MPH ave = 54 MPG.

48 MPH = 48 MPG
55 MPH = 42 MPG
65 MPH = 34 MPG
75 MPH = 26 MPG

On a warm day, with a warm but not too hot battery, you can get 72 amps of assist, which is about 32 horsepower of boost.

At zero degrees, with a cold battery, you might only get 25 amps of assist, which is about 11 horsepower of boost. With less boost, you end up using more gasoline.

HTH, and let us know what you determine.
-John

 

Hey guys, thanks for the responses. I really don't know much about cars myself, but I'll do the best to answer what y'all have asked:

I'm good about my tires. They were replaced at about 80k (IIRC), and I'm on top of keeping them properly inflated.

I'm not sure how to answer the fuel composition question. I fill up at only a few gas stations near me on a routine basis. Is there a certain type of gasoline I should be looking for?

I've never noticed any difference with RPMs, and while my commute has changed, my driving habits are pretty much the same (I don't go over 65 MPH unless I'm really running late, which is rare and I am pretty good about running on only the battery while on local roads). The issue I see is that my old commute was a very "flat" one, and the new one is much more "hilly". But this problem started before the new job.

I know to expect my car to run less effectively in the cold, but this problem is present in the summer time as well. I live in NJ, and have the whole time I've owned my MMH.

I used to get at least 400 miles out of a full tank. Now I'm lucky to get over 300.

 

The fuel composition question might be answered by looking at the fuel pump for a sticker stating "may contain 10% ethanol". Is your other vehicle--Saturn VUE also experiencing a loss of mileage? A loss of mpg during the winter months is common. I'm currently in the upper MidWest and am experiencing anywhere from a 4-7 mpg loss in mileage compared to the summer months.

 

The Saturn is having a minor drop, as is expected in the winter months. My MMH has had a drastic drop when I look over the life of the car... it's not just this cold spell that's responsible with my MMH.

 

I have the 2007 Ford Escape hybrid, and I noticed that when I changed tires from the original equipment Continentals to Bridgestone Dueler H/Ts, my MPG dropped about 3 mpg during the summer months, and it appears to be a more significant drop so far this winter.

 

I know I have bought new tires, but the gas mileage was dropping before I ever had to change them. I never noticed any significant difference with the new tires.

 

Hey guys, I've been using the Techron fuel system cleaner recommended to me in a different thread, and it's already made a big difference. I got about 40 more miles out of this past tank, and I'm going to fill up today on my commute home.

Hopefully this will keep up and my fuel mileage will go back to what it once was.

 

What does that Techron stuff cost ya?

If you live where you can buy E85 ( 85% ethanol ) it will also do a great job at cleaning. MPG will go down during that tank, but back up, way up, when you switch back to plain gas.

Don't put a whole tank of E85, but 50% of a tank with 50% gas will work well.

Ethanol is a very good solvent.