Significant drop in mileage - help!

[kalyanakrishna]

I am noticing a 25% drop in mileage recently. And I have no clue what caused it. Some details:

2003 MDX, 125K+ miles as of this morning.
All service done on time

Recent work:
Steering column replaced due to oil leak
Front axle replaced
Transmission oil changed

1 year ago:
New tires installed - bridgestone dueler h/l alenza - noticed a drop in mileage right after new tires installed (attributed it to the new tires till they wear in)

I usually get 19/20 in city and 23-26 on highway. However, since the move to central Illinois, the mileage has never been as good as it was but still hovered at between 18.5-20.5 mpg.

Since the last couple of months, it is now hovering at 15-18 and sometimes on highway gets to 20 mpg. Especially since the past month, it is hovering around 15.5-16 mpg.

My driving is not bad, I am very gentle with the acceleration and rarely ever engage in mileage lowering actions.

One of the things I suspect is the spark plugs. They were replaced as per the service plan (~100K) and I noticed the car was not as responsive as before and also noticed a slight reduction in mpg. The shop is very reliable and have done all service and other work on the car since 2.5 years.

I am not sure what I am missing and why the mpg would drop so suddenly.

[dons04mdx]

Was the valve clearance adjusted around 105K miles as well?

[mowashear]

23-26 mpg? thats pretty high....

Had an alignment done recently?

[RallyD]

Cold weather can typically cause a reduction in fuel economy. Did you move from a warmer climate to colder, Central Illinois?

Your tire pressure will decrease in the cold and cold air is more dense which requires additional fuel to be injected. Also in the cold, some people will let their car warm up before driving by letting it idle in the driveway.

[lion9mdx]

Is the torque converter locking up correctly? Was Honda fluid used for the transmission service?

After driving for a while, check carefully if any wheel is hotter than the one on the other side. If it is, you have a brake that's sticking on.

[nsxtasy]

In addition to the suggestions mentioned above, you might want to also check the items mentioned in this recent discussion:

Worried about freeway fuel consumption recently. Getting 16 MPG...

Originally Posted by kalyanakrishna

I usually get 19/20 in city and 23-26 on highway. However, since the move to central Illinois, the mileage has never been as good as it was but still hovered at between 18.5-20.5 mpg.

Since the last couple of months, it is now hovering at 15-18 and sometimes on highway gets to 20 mpg. Especially since the past month, it is hovering around 15.5-16 mpg.

My driving is not bad, I am very gentle with the acceleration and rarely ever engage in mileage lowering actions.

FWIW, the mileage on my well-maintained gently-driven 2004 is about what yours is now - 14-16 around town and 20 on long-distance trips. I've never gotten anywhere close to your earlier 19/20 in the city or 23-26 on the highway. So I can't explain why you would have been getting such high mileage earlier; what you're getting now seems normal to me.

[TheBigKahuna]

Did your local stations switch to a higher percentage ethanol fuel?

I took my 06 on my longest highway trip yesterday, and averaged barely 22mpg on the highway. I have my doubts any MDX gets much more than that.

[nsxtasy]

Originally Posted by TheBigKahuna

I took my 06 on my longest highway trip yesterday, and averaged barely 22mpg on the highway. I have my doubts any MDX gets much more than that.

[MDXROCH]

I'd be lucky if I get 21mpg on Highway. I Went to Boston from Rochester, MN a few years ago, my best was 20 on I90 at 70 mph. I'm avg 17 with 90% highway.

[phins2rt]

A lot depends on the wind. I've seen my mileage as high as 25.5 over 200 miles with a decent tail wind. I always seem to get great mileage going south between Oklahoma City and Dallas on I-35 (25+ mpg). Maybe it's all downhill?

[nsxtasy]

Tailwinds/headwinds and downhill/uphill stretches can indeed make mileage better or worse, but their effects are likely to even out when mileage is measured over the course of several tankfuls.

[androcathr]

Cold weather can typically cause a reduction in fuel economy

[yogi799]

Large amount of cargo and 15 passengers and 5 dogs inside the car can cause the fuel economy to plummet, too.

Do you guys think OP is such a dumbass that he would not know that cold weather and headwinds may change the MPG? Also, the winter gas suggestions. Pathetic. Have more trust in what we say/ask, most of us are not complete imbeciles who make stuff up - the reason lies under the hood. My mileage took a hit as well and it's a real drop - not more cargo, worse gas or winter weather. Come on. By the way, cold weather on a freeway probably makes no difference once the engine is warm. If anything, the MPG would be better as the AC if OFF....

[G. COLTON]

Originally Posted by yogi799

Large amount of cargo and 15 passengers and 5 dogs inside the car can cause the fuel economy to plummet, too.

Do you guys think OP is such a dumbass that he would not know that cold weather and headwinds may change the MPG? Also, the winter gas suggestions. Pathetic. Have more trust in what we say/ask, most of us are not complete imbeciles who make stuff up - the reason lies under the hood. My mileage took a hit as well and it's a real drop - not more cargo, worse gas or winter weather. Come on. By the way, cold weather on a freeway probably makes no difference once the engine is warm. If anything, the MPG would be better as the AC if OFF....

The answer to your question is yes. Not that he, or anyone else, is a "dumbass," but that they do not know about the items you list.

You would be surprised at just how little most folks really know about vehicles. You are showing lack of knowledge yourself with your disregard of the items others with knowledge have suggested.

George

[phins2rt]

Originally Posted by yogi799

If anything, the MPG would be better as the AC if OFF....

I don't know about you, but around here if I have five people in the car, no sun and the weather is cold I need to keep the defroster working to keep the ice off of the inside of the windows. For all the "dumbasses", this means the air conditioning is on, too.