I recently drove my "new" used 99 3.3L Grand Caravan Sport for a road trip from Chicago to Decatur IL for a job interview. I previously posted about how terrible my mpg is - 9 to 14.9 mpg city driving in stop 'n go Chicago, IL. Well, I just learned that the new Honda Odyssey isn't any better, as I met a person with one and he told me that he's getting 12 mpg city. So I guess the new minivans are just terrible for city driving (I sure miss my old 95 Grand Caravan 3.8L - worst 14 mpg city).

Anyway, on my drive from Decatur to Champaign - Urbana I drove about 43 miles, did 62 mph with strong A/C, and got 22.7 mpg. On my way from Champaign - Urbana to Chicago, IL I drove 132.9 miles, set the A/C to a milder midrange setting and recirculating air, drove between 66 to 70 mph -- and I ended up getting 25.8 mpg at these higher speeds! So all of this makes me wonder -- is it better to drive at higher speeds like 66 mph or higher -- so that the transmission goes into 4th gear ? At 66 mph I think I'm doing 2100 rpm -- I should have connected my Auterra OBD computer to record data. Of, course, my milder A/C settings might have been a factor, as well as unknown wind and altitude changes.

Does anyone know the transmission speed shift points for the Grand Caravan? Like when does the van go into 4th gear for ultra low gearing? I couldn't find any Google answers.

If anyone has observations on how they get better HWY mpg please post your info too. Also state what van model you have, the year, and engine size.

 

Best ways to increase mileage are:
New Air Filter
optimal air pressure for your tires
synthetic engine oil (more than pays for its self now that fuel is so high)
Drive 55, or 60 MPH. You dont have to go 65 if thats the posted speed.

These things listed brought me from 16MPG to 19MPG in my 6000Lb 4x4 Dodge Diesel. It might not sound that great but thats 20% increase in fuel economy.

 

my '94 GC would average 21-22mpg per tank, driving like a 13 year old

you have to get a lower restriction muffler put on, K&N or Fram AirHog airfilter (factory routing is cold air), so no need to mess with it

thats about the easiest that hasn't been listed

-greg

 

My van is already tuned up and I am using Mobil 1 synthetic. The point of my 1st post is that I got higher mpg driving at a higher speed! Maybe this is where the 4th gear comes into effect - above 65 mph?

 

then my thoughts are, that the trans will always end up in 4th/overdrive at pretty much any speed over like 30mph

but at cruising speed your rpms naturally will rise, & when 4th engauges & lock up happens, its sitting where the engine easily makes enough torque to sustain the speed happily, so it doesn't lug, or 'try' for that matter

heres a prime example, i went down to the ocean last september for VW week (i had alot of VeeDub friends at the time) with my buddy eric, now thats 2 1/2-3 hours of driving (about 163miles) averaging 65mph for most people....

...i got there just over 2 hours, & that was including a pitstop (rather prolonged) at a walmart to pick up some supplies, this was back when my van just had a short ram, no cat, volvo resonator (basically nuthing), my dual sidepipes, & wires, etc, it had 189K on it at the time, bald BFG tires, & my one friends system consisting of 2 10" subs in a bandpass, I rarely saw under 75mph the whole way, & i even raced this guy in a silverado from a light all the way to about 105mph ( i beat him baddd!!!), settled back down, noticed he was still in it, i punch it as he goes by, & i took her back up to around 100 again, just to beat him, eventully he turned off, & we got there, i only used 3/8ths tank of gas, now down in Ocean City its got a main road, called Costal Highway, speed limit is 45mph & its 4 lanes wide both sides, & runs up & down the coast, when its some kind of car meet or even senior week down there, it turns into drag central, & EGO bashing & whatnot


my van never saw 3rd gear down there, i was always running it out making alot of noise thru my sidepipes, & trying to race every golf, jetta, & anything down there, the van actully got alot of cheers (mainly fron the drunk people, lol) but needless to say it really should of blown up down there, i ran it that bad, i finally get close to empty, hit the gas station, it took 16 gallons to fill up, i did the mileage & gallon math, it came out to be 22MPG!!!

now that made my whole weekend, i ran the royal **** out of her, & was still rewarded good mileage & she never broke!!!

-greg

 

I can always feel my 97 3.0 slide into 4th. It's usually somewhere around 35-40 mph. I've been keeping up with my mileage on a local website that has a fuel logbook. I'm getting an average of 29.4 mpg. I would like to put an RPM gauge in the van. I really don't know why I'm getting such good overall mileage. I use Mobil Clean 5000 (3 qt) and Lucas (2qt). I check my tires every morning and make sure they're all properly aired, keep them rotated. I also got the K&N air filter. My plugs need changing lol, they have about 50K on them. Our daily commute is 15 miles (1 way) from home to work, all highway, and I drive that an average of 2-3 round trips a day. I probably do another 15 miles a day in town running errands and such. Perhaps the fact that I am on the highway a majority of the time (I never do above 60 on this particular highway, there's a trooper that lives and patrols along there) is the reason for my good mileage. I sure as heck won't complain about nearly 30 mpg with 203,700 miles on the engine and tranny.

 

take roof rack cross bars off, that shaves a dynamic 6 inches to a foot off your vehicle's height depending on speed you are traveling. less wind turbulance equals smaller vehicle profile when it comes to highway speeds

 

Hey minivanin I had a 95 GC 3.8L and it was real great with the mpg. Best hwy mpg of 30 mpg! I really miss my 95 GC.

What is the low restriction muffler you're using and is it loud? I'd like to put a Dynomax Ultraflow but it might be too loud.

When I draft behind a speeding semi I instantaneously get 30 or more mpg.

Having had the 3.8 and 3.3, I think my next van will be the 3.8L -- it runs lower rpms.

 

I wrote this back in November, But it still has merit.

97GC
I was recently in the junkyard getting the electric rear window cranks. And I picked up the trip computer for my van.
$10 for both parts.
Simple install, and quickly noted that we only got 16 MPG. Although it ran fine.
Well with a trip to Orlando in the coming weeks. And $2.79 a gallon for gas. I felt a checkup was in order. The van recently had plugs, oil and filters.
Further investigation found a few small problems.
A bad O2 sensor,
Improper inflated tires 32 PSI, (glove box sticker lists 35psi)
Removed the unused roofracks reduced air noise and drag.
I managed to get it up to 18.7MPG. Mostly suburbs style driving short trips.
Orlando came and went. The van was great. 2533 miles.
averaging 25.5 MPG peaking at 27MPG per tankful on the computer.

This was 5 passengers, fully loaded, A/C humming.
I have found the trip computer to be a great teacher.


So far the trip computer has taught me to keep the RPM's low when starting off. This is the biggest saver.
Approx 2K RPM will allow all 4 gears to shift. Only when possible, I try not to drive followers nuts.

After getting up to speed, Let off the gas very slightly.
You can keep the same speed, But increase mileage.


I now have a 05 Chysler T&C. The trip computer wont give me instantaneous reading.
And the T&C cannot compare to the GC in gas mileage.

But I'm trying to improve it.
Maybe synthetic oil.......?

[sm=gears.gif]

 

heres a link http://www.cardomain.com/id/malibuguy , i have videos of a few different set ups on my van & the muffler on my mothers (ultra flow)

i'm redoing my system on my van for a deeper, little quieter tone, don't gimmie wrong i love my current exhaust, just i wanna redo the whole exhaust over again, & i have a dual tip DNX muffler heading my way, i'm going to do 2.5 (from the manifold) into 3" i'll try to create an anti-reversion chamber there, into my 3" high flow cat, then get a smooth transition flowmaster reducer cone back down to 2.5", mandrel bends all the way back & into my new muffler, which will arrive monday i hope!

I'd recomend the ultra flow on your 99, & keep the stock resonator (which i reinstalled on moms since it was too loud for her) unfortunatly i do not have a vid of hers with the resonator back in place, but its very deep & pleasent, & like maybe 2 notches louder then stock, basically you barely hear it inside, but its definetly noticable outside of the vehicle

wait i just called my buddy, i'm going to try to get a video up of its current sound tonight!

-greg