2012 Dodge Grand Caravan +30mpg(imp)

[sbestca]

Hey guys, Canadian here, this is going to be in metric.
Bear with with me, I am just learning the L/100kms system too.
So, 10 L/100kms = about 30mpg(imp) and I have been able to beat that consistantly on a 4300 kms trip (that I am not quite finished, couldn't wait to post).

I am a 52 yr old machinist, Ind mech, and electrical guy. I've converted vans to 4wd and hot rodded just about everything I have ever owned, including lawn mowers. So I bough a Caravan because I liked my 99 and it fits my needs as a truck, camper, sedan, trailer tow-er and has the highests fuelmileage in a big enough vehicle to do the job. Fuel mileage, like power is never good enough, so I am tinkering.

Up to now pretty much base-lining the van. Fuel mileage has slowly risen in the first 16,000kms and seems to be flat lining. Fuel mileage is highly variable, from 8 to 10 L/100kms on typical 100kph highway trip and can drop down to 7 L/100kms at 80kph. Michelin (snow tires!) have lower rolling resistance (coastdown test) than the Yokahama's, but I cannot see it in fuel mileage figures, probably less than 0.2 L/100kms.

On this trip I left Nova Scotia with a basically empty van and went slightly more than 700kms on just under 69L of fuel. Hooray just better than 10L/100kms! But I had to do on average 90kph (55mph) to accomplish it, slowing down to 80kph on hills and up to 110kph on downhills. Pulse and Glide does not work at all with van, as does neutral coast because it shuts fuel off on coast. I maintain constant throttle on hills and gain and lose to see indcated fuel mileage at 8 to 9 L/100kms. Gave about 750 kms to a tank.

First mod during the trip was to saran wrap the upper grill. Engine temp rose from 1/3 to just under 1/2, warm up was faster, Indicated fuel mileage increased into the 7 L/100kms range and I got over 800 kms on a tank at just over 9.2 L/10kms for the tank actual.

The saran wrap shedded in the rain and snow (temps above and below freezing) so I tore it off and sure enough lost fuel mileage on the next Tank.

So, I bought some coreplast and made a grill cover. Same good results as the saran wrap! Not content with just that, I made a lower grill cover 1/4 into that tank. Outside temp is -4 to +8 and temp needle is runnng just over 1/2. Same place it runs in the summer time. The "outside temp guage" is showiing +9 to +30c temps so it must be inside the grill or engine compartment or air intake. Fuel mileage has improved into 7.5 to 8 range at 100 kph. I got 900 kms range on a tank for 8.2 L/100kms with some drafting (2 seconds behind vehicles) through Quebec route 20 and into New Brunswick.

This last tank I followed a heavily loaded cube van at 90kph max down to 80kph on hills. My (inaccurate) gauge was showing 6.2 L/100kms and Showing that I will get over 1030kms on this tank (usually accurate). I am 436 kms ino the tank and still showing over 1/2 tank which is about 74L max that I have ever put in.

[sbestca]

Ok, didn't quite make the 1000kms on this tank, got home and got it filled up at 608kms and only took 43.7L for 7.2 L/100kms! Tank forecast at fillup was 970 kms, forecast on the new tank was 1001kms. No drafting and lots of hills on the last 300kms.

Steve

[101Volts]

Hi, I drive a 2000 Caravan myself. If you haven't done this and don't use it, I recommend removing the roof rack. There was a spare tire plus the roof rack on the van I drive and after they were removed, It upped the MPG. I'm not sure what we get in general despite the van's stats as I haven't compared miles to the pump and the ScanGauge II isn't calibrated; The gauge sometimes says we get over 40 on some highway trips but I can't say that's quite accurate, It might be closer to 30.

[sbestca]

I had a 99 Caravan before this that I bought new.
It seemed to deliver better "around town" fuel mileage than this 2012 does.

The roof racks on the 2012 can be refitted into the side supports so there is no cross pieces struck in the wind. Much better than the older design. Much more aerodynamic. I use the roofrack a lot so I am prone to leaving it in place. The spare tire is stored under the floor between the front seats. I have not looked at it so far. With modern tires it may not get used very often, but is still darned nice to have if I ever need it. Hard choice.

My economy measuring tool is the on-board economy indicator, which reads out an accumulating average of L/100kms that can be reset at any time for a new condition. The first couple seconds are not very useful but gives a reliable and repeatable readout on flat ground. I have tested it against full tank measurements and found it slightly (about 5%-10%) optimistic. I use it as an ongoing test tool and not as a quote of what I am getting for mileage.

The grill cover works for sure, giving 0.5 L/100kms gain in this cold weather. I think part of this gain is from the cold weather. The grill cover warms the rad and engine and air intake up to 10-30c. The warmer air vapourizes and burns fuel better and an open thermostat saves HP due to not deadheading the coolant pump.
Grill cover gains:
1) Aerodynamics, no drag through the engine compartment or under vehicle
2) warmed intake air, better vapourization and combustion (in cold weather)
3) higher engine temperature, better combustion, less oil friction losses (in cold weather)
4) Thermostat runs open, less coolant pumping losses (in cold weather)

Considering the grill openings, radiator and waterpump pulleys are sized for pulling a trailer through Arizona, a cover should reasonably work year round here in Canada. There was NO tendency to over heat in temperatures up to 9c no matter what speed or hill. Waterpump pulley ratio may be another place to find savings. Sizing the crank pulley down slightly and the water pump up may help?

Drafting was worth 0.5 to 1.0 L/100kms fuel mileage gain, depending on speeds and type of vehicle drafted. The best vehicle to draft is the largest and lowest to the ground. Ironically 18 wheelers are not that much of a gain as measured by my fuel mileage indicator. I think the gain is from having a sheet of air moving near ground level as SUVs and 4wd pickup trucks do not show much gains either. This sheet of air seems to kkep moving a long way back from the lead vehicle and is not affected much by side winds. There is no need to be any closer than 1 second behind the lead vehicle and the effect is still measurable 2.5 seconds back. 2 seconds back is perfect for safety and economy.
Best vehicles to draft:
Tour buses: usually constant speed but near max posted speed
Moving vans: same but lose speed on hills, which is good for mileage, hard to follow
Car hauling or low-boy trailers: Some danger of rocks thrown up or dropped off the trailer.
Cube vans: my favourite as they tend to travel slower
Tanker trailers: I don't know why but I get good numbers off of these, watch for rocks
Low large cars
Minivans
18 wheelers: watch for rocks thrown
Cars in general, especially a slower one is better than an overly fast bus
SUVs, Pickup Trucks: not so helpful to draft but better than nothing

Steve

[101Volts]

I wasn't saying "lose the spare tire". What speed are you going on highways, Usually?

[sbestca]

Originally Posted by 101Volts

I wasn't saying "lose the spare tire". What speed are you going on highways, Usually?

Given my own preference it would be as fast as I can get away with, but with age I have learned to slow down and enjoy my thrills on an off-road machine. Typically I travel the speed limit or 8kph over on cruise control if I am pushed for time. This trip was pretty much around 90kph with a few exceptions.

On level ground the best speed for fuel mileage is as slow as you can go in high gear, which is about 70kph and only returns slightly better fuel economy than 85kph which is where the fuel use tends to increase with speed. There is a huge difference between 100kph and 110kph so I rarely exceed 100kph unless drafting or on a downhill. Hilly terrain returns better fuel numbers if I accelerate to 100kph at the bottom of hills and just crest them at 70-80kph, which incidentally tends to be how heavily loaded trucks take them. No longer do I curse those guys, but follow behind them soaking up the fuel mileage benefits.

Drafting a large low vehicle can overcome the advantage of low speeds.
Following a tour bus at 110kph returns the same fuel economy as plodding along at 90kph on my own. This is a no-brainer, give me the speed!

Highway safety is important to me. On dual lane highway where there is ample opportunity to pass, I have no problem doing 20kph under the posted limit. If traffic is heavy or single lane, I speed up to the general flow for safety, plus I am gaining the benefit of drafting. I don't hold a long string of vehicles behind me because some idiot will try to pass where it is not safe.

I used a scantool in my Taurus to learn to increase mileage. Interesting that the 97 Taurus responded to pulse and glide where the 2012 Grand Caravan did not. The Caravan responds to "Rolls Can'ardly" driving, rolls down one hill, can hardly make it up the next! It has ample power but sucks fuel to use it.

Steve

[101Volts]

The FE (Fuel Economy) of your van may benefit from this thread:

http://ecomodder.com/forum/showthrea...you-15182.html

(Edit: The next paragraph is false. The van gets higher economy between 55 and 65, Coasting. Do note at which point you get the best economy, Though.)

I've noticed this too; When on a flat (Generally speaking; There are many hills and slight inclines where I live) If I'm going 35 MPH/56.327KPH I get higher FE than at 45 MPH/72.4205 KPH. Going 65 MPH/104.607 KPH on a highway over 55 MPH/88.5139 KPH really kills the FE even though the ScanGauge II isn't calibrated properly yet.