Help Me Explain this

[WorkingOnWise]

This is a long post, but please take the time to read it and offer up any words of wisdom you have. If it is what it is, great! If it isn't, I have got to learn what I am doing so wrong!
Ok, I have a 1995 Mercury Villager GS minivan with a 3.0L V6, an automatic transmission with overdrive and a lockup torque converter, and 140k miles on it, and it weighs 3800lbs (by manufacturers stats. I will be weighing it tomorrow as part of my baseline information) It has 4500 miles on the petrol based engine oil and napa oil filter, it needs a set of tires pretty soon (one tire has a low speed shimmy - sure sign of a shifted or broken belt), and it is bone stock.
It runs great, but at idle it has a very slight misfire, so I'm sure it could stand a fresh tuneup. I have no idea about the age or the air filter, but it at least passed a visual inspection.
I tell you all this to show that it is your regular old well cared for minivan. Nothing at all to think that it should perform in any way out of the ordinary.
The EPA said in 1995 that it gets 23mpg highway, 17 city. When I saw those numbers, my heart sank a bit, because I realllllly want 40mpg from this van. I have heard a few here and other places wish me a disbelieving good luck.
Which brings me to today.
Today was the day I was going to get my baseline mpg so I could officially launch my business, which is selling mpg improvers that have been tested by me, and actually work. If I find it to be junk, I will be more that happy to tell anyone who asks!
We filled up at the BP on M28 and F13, then drove down F13 to US2 and into Rapid River. We turned around and headed back to where we started from. Denise wanted to go look at a scenic stop and I told her if we did, we would have to stop there every time we did a mpg test, so we dont throw the results off. Well, my wife is pretty girly, and is very good with having to stop at the same pretty place every run.
It added 14 miles to the test run, so that was fine. It was still 55mph, as is all the roads we use on our test route, so it was still a highway speed test.
It was 70 degrees f by now (2:20pm) and getting sunny, so driving in no shade and no AC and the windows was beginning to really suck. We dropped both windows for that 14 miles to cool us and the interior of the van off. In my mind I am trying to imagine the brutal impact it was having on my test results!!)
Once we got back on US2, the windows went back up and the fan went back on, still no AC. Well we got back on F13 and headed north to the BP where we had filled up at in the beginning.
We chose F13 instead of M28 for three reasons. One, it runs right thru a national forest and has pretty good shade for most of its 37 miles. Two, it is a kind of curvy road with constant trees on both sides, so the wind really cant affect the driving. Between the curves and trees, it is nice and calm. Third, it is fairly hilly, which isn't great for big mpg numbers, it does help with giving a more realistic highway test, at least in my mind. We just set the cruise at 55mph and kept the van away from the trees as we went down the road. No tricks to help the mpg, even when they really would have mattered, like when the van had to climb the 6 hills where the cruise computer increased the throttle so much that the transmission dropped out of OD and down into 3rd.
So, theres the scenario for you.
When it was all said and done, my mpg for that 114 mile run, was 30.5 mpg.
I had seen another pretty impressive number from this van last month when we drove down to Indian River, about 160 miles. On that trip, we got 32.2 mpg. I checked the distance against both gps and a paper map, and reverse calculated the fuel used and fuel paid for, seeing if the pump was maybe off, in my favor (I know I know, fat chance!) because I just didn't believe it. We drove the same way on that trip as we did on todays test run, and 32.2 was the number. I dismissed it as some variable I was unaware of and therefore couldn't control, which was whacking my results.
But today I got 30.5. And Saturday we drove a total of 112 miles on a trip to Marquette and back, including 16 miles of driving around in the city, up and down some pretty stout hills, with 4 adults tha whole way, which added 400lbs to the vehicle weight over what it was today. On that trip we managed to get 26.5, and we weren't even thinking of mpg. We were just out for a fun day with the family.

So, what in the world is going on that I am getting a repeatable 30+ mpg from a van that, when it was brand new, the EPA only managed 23 mpg from?

[Wyldesoul]

I think it may be that you aren't treating it like a hot rod. Most people who drive cars think that any pedal has only 2 positions, fully on or fully off.

VROOM! SCREECH!

You get that a lot on the road. So your car may be getting that good of MPG merely because you're not crazy...
That is, if it's the 2008 revised EPA and not the 1995 original EPA. If not.. You lucked out?

[theholycow]

Those numbers certainly aren't hard to believe. You're talking about conditions more perfect than even the old EPA tests were.

[R.I.D.E.]

Basically your van is a station wagon version of an 89-94 Nissan maxima.

If I remember correctly the 89 Maxima we had would do close to that MPG, but we usually drove at higher speeds.

Your engine revs are probably very low at 55 max speed, Hills can actually help your MPG if the transmission drag is low on the downhill slopes.

Those old Maxima powertrains were among the best ever built by anyone anytime. Engines were final fitted with 4 different standard bearing sizes and 4 different piston sizes depending on final finished machine dimensions. I have seen them go 350k plus miles with ease.

The hot wire mass air flow sensors tended to run lean when they were getting somewhat tired, the idle symptom you describe was one symptom of a weak meter.

Combining this with the fact that the Quest was not a large Minivan (same as villager) and probalby had decent aero, especially for a Minivan, I don't think your figures are wrong or even amazing. I would consider them exceptional, and doubt you will be able to do much to make them better, but good luck on your 40 MPG goal.

regards
gary

[WorkingOnWise]

Originally Posted by theholycow

Those numbers certainly aren't hard to believe. You're talking about conditions more perfect than even the old EPA tests were.

Can you qualify that for me? My reason for asking is because This is the condensed version of how me and my wife both drive, day in and day out.

Get it, start it up, drive gently till the temp gauge is in the normal range. Always accelerate smoothly and unrushed. Set the cruise for the speed limit if you'll be driving that speed for more that 5 minutes. Never drive faster that 55.

The condensed version of how we do a mpg test is this:
Drive 5 miles to BP. By then, things are warm enough for my purposes. Fill up the tank, right to the top of the filler neck, at pump 1, facing west. Pull arond, make sure the tires atr at 35psi. Pull out onto F13, smoothly accelerate to 55, and set the cruise. Keep the van away from the trees. Drive to Rapid River, then turn around and come back to BP. Fill up again, and do the math.

To me, this is a super simple way to test and drive, and I cant imagine anyone, even the EPA, not being able to drive this way daily, and for sure during a test where variables must be controlled.

I do a better job that the EPA with my highway mpg test procedures?

But I cant argue with my results either.... 30.5 mpg no matter how I tried to figure it!

[WorkingOnWise]

Originally Posted by R.I.D.E.

Basically your van is a station wagon version of an 89-94 Nissan maxima.

Do I remember correctly that the 89-94 Maximas had the same V6 as the 300Z of the same generation? Do I have that same V6 in my van? If so, I totally get why it is such a great running engine, and have a little easier time believing 30.5 mpg. I did know that my van was a Quest dressed up in Mercury clothes, which is why I liked it so much. Nissan has always been one of my more respected manufacturers.

[Wyldesoul]

The EPA, at least in the 80's would gather the MPG in just that way, be gentle, but still "realistic" in the "driving."

But nowadays, they judge the MPG by the average way to drive, which is in no way gentle, and in no way controlled. As I said... Most people drive in the vroom screech manner, and the newer EPA takes that into account.

[theholycow]

Originally Posted by WorkingOnWise

To me, this is a super simple way to test and drive, and I cant imagine anyone, even the EPA, not being able to drive this way daily, and for sure during a test where variables must be controlled.

I do a better job that the EPA with my highway mpg test procedures?

Nearly everyone on this forum does, the way you are thinking of it. I'm beating the EPA by 30 to 40% every day in two unmodified relatively inefficient vehicles. I'm making a decent effort but nothing extreme; I don't even do any EOC.

When the EPA does a "good job" testing, that means that they've accurately represented the way that most people drive, not that they have squeezed the best mileage out of it or even driven it smoothly like you describe.

When my truck was brand new, I had results similar (though not quite as good) to yours using similar driving habits. Rated 16 highway, I would set my cruise control to 65 or 70mph and drive long highway runs with loads in the bed or un-aerodynamic stuff stapped to the ladder racks, and I'd get 18mpg on those runs.

There's nothing inherently surprising about your results, you're just reaping the fruits of efficient driving effort.

[R.I.D.E.]

WorkingOnWise:

You have created the ideal scenario in your test. Warm engine, practically ideal driving situation, very little braking. National parks dont have areas where you run into typical stop and go situations. Fuel up and drive at 55 or less almost always in overdrive. No cold starts. Engine RPM probably just over 1500.

The 3 liter Nissan V6, was a Hemi, cross flow, 2 valve design that had very good low end torque, as well as decent high end performance.

That same engine was used in Rutan's Pond Racer a plane designed to race in the unlimited class with planes like the Bearcat and P51. They got 1000 HP from that engine but reliability suffered at that 6 HP per cubic inch level of power.

The Quest-Villager vans were designed to be close to the original Chrysler Minivans dimension wise. The rear axle was a simple beam with leaf springs, to keep suspension intrusion into the cargo area to a minimum.

Worst problem with that engine was broken timing belts, which could wreck the engine.

It was used in the 300ZX (not transverse) and the earlier Pathfinder trucks, as well as some of the pickups and even the later 200 SX models, as well as Maximas from 1985 until 1994.

Our 99 Maxima had the later all aluminum 4 valve V6 and weighed only 2800 pounds. That was one of the best cars ever made. I would stack it up against any manufacturer on the planet.

My Civic VX was rated at 56 Highway (old EPA). If I duplicated your test situation I would probably get at least 65 MPG, maybe even 70.

regards
gary

[WorkingOnWise]

So the consensus here is that my results are what is reasonable to expect with the driving style I use and the conditions I drove in.
I LOVE that, and here's why. In the part of Michigan I live, everyone can drive the way I do. Most places you go are 35-50 miles apart, with low traffic 55mph highways in between, and no stop lights till you get into the small towns, which are quite often 1 mile or less in length.
So, I am in the perfect place to show what a dramatic impact road choice and driving style can have on mpg! The best part is that the other 2 roads I could have chosen are just about the same, but a bit straighter! Still trees almost everywhere, though admittedly not as well protected. These other roads are in better shape, but not by much. I'll have to do the same type run down M28 from Wetmore to Newberry and see where my mpg is at. I'm confident it will be 30.5 to 31.
So I accidentally did 2 things with one test today.
I proved that anyone can outdo the EPA by a respectable margin around here, and I got a solid reliable benchmark mpg for my van so I can accurately gauge where I get the best benefit from future mods and products.
More reasons why I love it up here so much! LOL

I am all too familiar with the broken timing belts on these vans! I have done 4 or 5 of them. Lucky for the owner in each case, the engine was fine. But as a warning, every book and resource I have says it is an interference engine. I dont want to think about mine. I just found out that A) no one knows if it has ever been replaced before, and B) the mechanic who told me it was fine made that decision on a VISUAL inspection! Yup, he looked at it, saw no frayed edges and no missing cogs and declared it good! UGH!

Thanks for the details on the engine Gary. It boosts my confidence in the engine for durability, and explains why when there is a need to pour on the coal, this little minivan does not hesitate to respond! I test drove an 89 na 300ZX and decided not to buy one. Way too fast and way too much fun to drive for me at 20! 65mph entering a 45mph on-ramp and the salesman says "get into it, she'll hold nicely up to at least 85"
Yeah, I got half the formula between my fenders. Plenty of fun for me!