Having MPG issues, whats wrong?

Gotcha! Nearly impossible for me to find ethanol free around here. You are a lucky man.

 

Hahaha that is being a little generous.

 

Man, and I thought it was bad when ethanol started showing up in the 89 around here. I guess I can be thankful it hasn't crept into my 91!

 

So first off when I did that post I just threw rough numbers in there as an example of a "truck" to show the relative effects of aero drag and rolling resistance.

But with a little searching I did find this for the 2012 Tacoma:

http://pressroom.toyota.com/article_download.cfm?article_id=3139

And in case that link dies at some point, for the benefits of future generations the data that is found on page 4:

0.357 - Base 4x2 RC
0.368 - Base 4x2 AC
0.394 - All Pre-Runners and 4x4
0.419 - Anything with Off-Road Package

Didn't see anything on frontal area in the document though...

 

All our available fuels here except Chevron 94 are 10% ethanol. I use 87 for the Tacoma.

 

Why would an off road have different cd then a prerunner? They are the same size and shape with more features including locker.

 

Secondly, how can I find out the amount of ethanol in each individual grade at a local station? We just have a disclaimer that says fuel contains up to 10% ethanol.

 

Ethanol is cheaper than gasoline. 'Nuff said?

 

If it says up to 10 then it generally is all the way up to 10.

 

http://pure-gas.org/index.jsp?stateprov=NY

 

I found that perplexing as well. But I think the reason is that the TRD OR comes with the "engine skid plate" while no other option package does. A lot of the drag coefficient comes down to what happens to air going under the vehicle (one of the reason we see new trucks coming out with air dams on them to improve their EPA mileage stats). So presumably something about the "skid plate" is changing the drag under the vehicle.

The other related difference is the height of the vehicle - a taller stance resulting in more air under the vehicle can increase drag. But in this case the OR and Sport have very similar wheel diameters so it must be something else like the skid plate making the OR "special". But ride height is probably the reason the Pre-Runners and 4x4 are worse than the base 4x2.

 

I don't think that answers my question, I am asking how to find gas with lower amounts of ethanol.

That's my thinking. All stations here say that.

Do you think a skid plate would make that much of a difference though? Since it is oriented pretty well as far as the angle of it, I also don't think it acts as an air pocket. Oh well, I could be wrong. And yes I knew the taller stance would affect it, but I just thought PreRunners and TRD OR models would have the same Cd.

For what it's worth, I only lost 1 MPG when I went from 3" lowering kit to 2.5" lift kit. That was at 60 MPH.

 

I honestly haven't a clue. I just know the skid plate is one obvious thing different between the TRD OR and all the others and that things on the undercarriage can make a difference. Like I said, I am a bit perplexed by the difference and have no idea if the skid plate is the reason or something else entirely.

Thanks for the data point! Yeah, these Cd differences are not huge and at a 60 MPH are only one of many factors affecting the MPG. Was more of academic interest.

 

Cleaning my MAF sensor and replacing my PCV valve gained a few mpg back personally. Also improved performance!

 

How many miles were on your Taco when you did that? I'm at 76k.

 

I just did it 2 days ago at 134,000 miles. It was well overdue. Some people here do it once a year

 

I don't see the skid plate adding that much to the CoD. Maybe if it were the non-functional hood scoop, the skid plate, and a couple other things that create air-pockets. But not just the skid plate itself.

 

You are correct, I was also considering that it was an error. If statements don't come from Toyota itself I usually take it with a grain of salt. Once you become addicted to your truck you notice some online publishers have bad information

You're welcome. But is Cd not a very large factor at highway speeds? I read a chart one time mentioning that lower speed hinderances were comprised of 70% weight, 30% aerodynamics, and that at higher speeds it was the reverse, 70% aero, 30% weight. I think perhaps a more accurate statement would be, height is not a large factor on Cd as other drag-inducing features such as shape or taper?

For example, I'm hoping to one day (somehow) make an aeroshell (A camper shell that tapers at the rear to satisfy the teardrop template) to replicate what others have done on Ecomodder.com for an increase of nearly 4MPG at highway speeds. That must make a big difference in Cd.

I'm a 4th semester Mechanical Engineering student by the way, and have been proven wrong before so don't take everything I say to be truth.

That is awesome. I wonder if I can replicate those results at 110K miles on my 2007. I'm always looking for more MPGs.

I don't think the hood scoop hurts that much due to not a lot of air flowing at that part of the hood. So the fact that it is nonfunctional contributes to the fact that it doesn't hurt drag. Win/lose!

Now sell me your bumper. It's increasing your Cd.

 

Keep us posted! Curious to know if it was just a fluke or if mine was just really awful. Also, brake cleaner cleans it nicely just a few sprays on either size and it looks new!