I have a 2005 Grand Caravan and it gets from 14-17 city mpg , and up to 20mpg if I get the Interstate. There seems to be a lot of magic elixirs out there claiming better gas mileage, but is there anything I can do that will really help? I have a 1500 mile road trip planned for this weekend.

I will:
change the oil
check the tire pressures

What else can I do?

I should probably get a tune up but was hoping to put that off a bit. I'm not sure I can do that myself?

 

I also would top off all the other fluids and replace the air filter.

 

The best way to keep good gas mileage is to keep your car well maintained. Depending on when the car was last tuned up that might be in order as well. Changing spark plugs and wires isn't that difficult, though I understand on your generation of GC it is recommended that you remove the wiper arms and cowl to access the spark plugs on the firewall side of the engine - not sure how difficult that is.

There are also a number of ways to improve your mileage that are free:

• Remove unnecessary weight from the car (might not be practical on a 1500 mile road trip, but just driving around town it might be)
• Try to follow the owner's manual guidelines for putting weight on the front and rear axles to the extent possible for your passenger/cargo situation - this will prevent the van from sagging on the back end
• If possible in your passenger/cargo situation, try to load everything inside the van and avoid loading anything on the roof. If you are not using it remove the luggage rack crossbeams. This will reduce drag.
• Accelerate gently - no need to race a Mustang out of a red light
• Use cruise control where it is safe and practical to do so
• Don't exceed the speed limit - this has the added bonus of keeping you out of trouble with the law

Any cheap "magic elixir" that claims to improve mileage is probably a hoax and is absolutely not a substitute for good maintenance. I believe that some threads on here have said that any real fix to improve your gas mileage would cost you at least $500.

 

...and of course check the tire pressure with a known good gauge. A pound or two on the high side of nominal will help.

Dave

 

thanks for all the great suggestions!

Of all things I'm carrying myself, some gear, and 11 cases of wine! i take it I should stack the cases over the rear axel then?

Also I went to remove the crossbars onthe roof rack, and they loosen, but not all the way, so the little clamp on the back side is there. Do I want to keep turning the **** and forcing the clamp off, or is there a technicque for removing it from there?

Yeah I have a great accurate digital guage and just check. Rears were dead on 35, but driver front is 39 and passenger is 31! I'm guessing 36 would be perfect?

Thanks again.

 

As long as the gear and 11 cases of wine don't cause the vehicle to sag in the rear or exceed GVWR or GAWR then you should be okay. The rear axle can handle a higher load before reaching GAWR because it's not holding up the weight of the engine, transmission, etc. If the vehicle sags in the front or rear then you are increasing drag and likely messing up the suspension as well.
I'm not entirely sure how the crossbar clamps are constructed on the 4th gens but on my '08 at least one of the ***** is stripped where the plastic **** meets the actual metal screw, so no amount of turning will remove it. So I can't follow my own advice on my own car.
Refer to the sticker on the driver's door pillar for proper tire pressure.

 

When it comes time to replace the tires, do some research on a place like Tire Rack to look for fuel saving tires.
A couple of years ago, I replaced the tires on our van with Michelin Hydroedges. While I like the way they handle, they had a noticeable negative effect on the mileage to the tune of at least 2mpg on the highway.

 

.........I have the same year van and was making the same mileage{atrocious I think} Had a partially plugged cat and read that CATACLEANwould help.was reluctant to try it but for 20$ i figured on giving it a go...I was shocked..although it didnt clear the engine lite gas mileage jumped to 27 mpg {canadian} highway.It also cleans the injectors...so you decide..

 

Couple comments:

1) Weight means absolutely nothing on a steady state highway trip, assuming downshifting on hills is rare and you have sufficient air pressure in your tires to carry it. My caravan gets about 23-24 mpg on the highway at 65 MPH either totally full (packed to the roof with 7 passengers) or totally empty.

I have driven vans and trucks for well over a million miles and know this to be true. Gas mileage is a function of the vehicles shape and size. However gas mileage will suffer when loaded full in mountainous areas where downshifting is necessary and brakes are needed on the other side of the hill. Basically the stored energy and added throttle up the hill is wasted in downhill braking. This results in reduced efficiency. The wider ratios in the 4spd will reduce economy on hills that require downshifting or more horsepower because the RPM rises. If the extra weigh results in downshifting to hold speed on downhill sections the gas mileage will also suffer. I hate this Dodge tranny "feature", I'd rather speed.

2) Gas mileage is a function of speed, especially in vehicles with large frontal area like a van or SUV. Dropping your speed from 75MPH to about 60 MPH will cause highway fuel economy to rise from about 20MPG to about 24 MPG. Time is money, so most people would rather drive fast and get there quicker.

3) Fresh spark plugs and wires will help economy if you have occasional misfire due to higher miles on the ignition parts. Changing them once every 100K mi with full platinum or iridium should be good enough.

4) Obviously full synthetic oil provides maximum efficiency.

5) Dragging brakes is the most common problem plaguing GC. If your caliper pins or brackets are rusted or the e brake cables are rusted, the brakes will not fully release. This leads to poor economy, as much as 10% or more, not to mention having to do brake jobs too often. Just jack up each corner and see if the tires spin freely. If a brake is dragging, you will need to repair it.

6) Don't run a roof-mounted cargo box. They totally destroy the aerodynamics of the vehicle and increase frontal area. These units eat gas like you wouldn't believe. I own a streamline shaped box from sears and it costs about 3 mpg which equates to about: 1500mi x gal/20mi x $4/gal x 0.15= $50 cash flushed on your trip

ps: modern tire design won't affect gas mileage 2MPG or 10%. That is the sort of difference you might see between today's latest super high economy green hybrid radial tire design compared to the cheapest 2 ply 1960 bias ply retread tire. Tire manufacturers are trying to squeeze fractions of a percent more economy out of today's tires, so figure a couple tenths max from best to worst. Tire pressure is the major factor. I run 38psi in my GC.

 

All great suggestions. One missing (I may be blind). Work the traffic lights in town and not just the light dead ahead. If you're well back from a light that's red or even been green for a while, slow down or better, take your foot off the pedal and coast. Gauge your coasting speed so you don't have to come to a complete stop. Any momentum will save you gas as compared to accelerating from a dead stop. Use any opportunity to coast such as down a hill or approaching a stop sign. On highway off ramps slow down well before exiting. The more you hit the brakes the more gas you're wasting. In all these situations, familiarity with the roads and traffic lights helps but you can still practice it to an extent anywhere you're driving. Plus, don't be a traffic hazard. Only practice this when it's safe and courteous to do so.

I inherited our van from the wife when we (she) bought a new car some years ago. She "isn't as inclined" to practice what I preach, at least regularly. She was getting around 19 MPG in mixed driving. I am getting 21 and sometimes 22 mpg. Not a major difference but add that up over a year and you're potentially looking at a couple of nice meals or a case of scotch.