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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
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