That’s par for the course… I’ve owned four or five minivans since the mid-80s, and that’s about what you’re going to get. Inflating your tires or making other adjustments as suggested might help boost you a few mpg, maybe to 20, but not to 32.
How fast do you drive on the highway?
I drive my '98 Caravan like the proverbial grandmother (accelerate very gently and keep it under 55 on freeways) and I still get 19 mpg at best. Even worse in winter.
I would have issues…in fact I do. I have an '05 Ford Freestar with the big V6 and I average 14-16 MPG. My solution will be to trade it in for something a lot smaller as soon as I’m financially able…if the cost of gas doesn’t bankrupt me first.
Minivans are not very aerodynamic. A Lincoln Towncar with a 4.6L V8 will get around 27 MPG on the highway (I’ve rented a few of them). I never realized how bad vans are until I bought one.
It is handy for hauling cargo around and nice if you ever have to have 7 people in a vehicle. And the DVD player in the back keeps the kids quiet. 
That’s another point I wanted to make. I took the Freestar on a 300 mile out of state trip last weekend and drove the US Highways most of the way (actually trying to conserve fuel). I kept it under 60 the entire time and had the cruise control on 45 for about 70 miles. I’m not ready for another fill-up yet but I had 300 miles when I hit 1/2 tank. I normally get around 425 on a tank (25 US gal.) and it usually plummets once it’s past the 1/2 mark, but I still think I might get 500 out of this tank. I’ll find out when I fill up again but 500 would indicate 20 mpg or better if the tank’s not completely empty.
If that actually happens, that’ll be a 5 MPG difference just by keeping it under 60.
:smack:
However
600Km is 372 miles.
100 liters is 26.41 US Gallons or 21.99 Imperial Gallons.
372/26.4= 14.09 MPG US Gallons
372/21.9= 16.98 MPG Imperial Gallons
McDtM made the reverse error from what I did. He converted to US gallons and then compared it to the Canadian numbers that are based on Imperial gallons.
The lesson here is that we have to use consistent (and labeled) units or assumptions will make an ass out of you and me ( particularly me in this case).
Stainz You have to realize that cold weather really destroys fuel mileage. There are some other factors that I will get to in a minute. In addition as I mentioned before IIRC BC uses oxygenated fuels during the winter. This type of fuel gives you about a 10% mileage hit in my experience. Also vans have the aerodynamics of a barn door. If you drive fast, wind resistance will kill your mileage.
Now could it be a mechanical problem? Yes, but most of these problems will set a check engine light.
Let’s go over the suspects.
Fuel leak Possible, but IMHO not very likely. You computer is designed to pick up a hole that is greater than 0.5mm (some cars 1.0mm) If such a hole is found, a check engine light would result. While it is possible that a pin hole on the pressure side of the pump might go undetected by the vapor system, I would think the eau de Petro Canada would be a big tip off.) It can’t hurt to look, but I would not bet the farm on this one.
Bad plugs or clogged air filter. Quite possible that a clogged air filter has the adaptivity of the computer all the way to it end stop, and will at some point in the near future trip a code (and light) for reaching it’s limit. Plugs? If you are in there, replace them is my advice. New plugs are like chicken soup when you are sick iIt can’t hurt and it may very well help.
There is also a possibility that a brake may be dragging, or the transmission is not shifting into the highest gear, which will result in increased fuel consumption.
Now I will give you what I consider to be the #1 #2 contenders for what the issue is. #1 is your van is old enough that the thermostat could be bad, or has been replaced by someone who put in one that does not get the computer all the way out of warm up mode. I know on the cars I teach on, if you replace the 95C thermostat with an 75C or 80C thermostat your gas mileage will suck donkey balls as the computer thinks the engine is still cold and it is still in warm up mode. A shop can check the temp of the coolant leaving the engine by using an infrared thermometer. That temp should be within 1 or 2 degrees C of the rating of the thermostat. If it isn’t replace the stat. Do not put in a thermostat that is rated at a lower temp than the factory unit. And the #2 most likely culprit is a engine coolant temp sensor that is reading a lower temp than the engine actually is. While the computer should detect a bad ECT sensor, if it isn’t all the way bad, it might slip through the cracks. A shop with a scan tool, and the afore mentioned Ir thermometer can check this is about 1 minute.
You are right-I drive a SATURN VUE (4 cylinder, manual transmission). If I keep it at 55 MPH, I can get up to 32 MPG (warmer weather), If i exced 60 MPH, the gas mileage drops like a rock-at 65, I’d say less than 23 MPG.