My comments on this whole thread from the very first post since i've studied Van Fu as well... : )
Gave thanks for finding out a manual transmission swap was possible on the dodge caravan using the neon transmission... that's interesting to me. That being said i'd never have anything but the earliest or the latest Caravans - dodge just CANT make a good engine or auto transmission since their original 2.2 until very recently it seems. Endless endless trouble and thats why many are sold. Sticking in the 5 speed would solve the auto transmission problems but your still stuck with an engine that eats head gaskets every 30,000 miles or so if your unlucky. (if a dodge expert can counter this i'm all ears, I like the dodges outside their powertrain but those who have had them, this is what they tell me until they angrily dump their stuff later)
That said the original Caravan was pretty unaero anyways - tolerable mileage due to small displacement but you think you could do better with small displacement combined with good aero. Good for an around town minivan though, actually among the best mileage for an around town minivan! Unfortunate there's no good dodge engines between about 1990 and 2005 by the sound of it.
Else it should be the king... the newer ones are quite good aero. The earliest 1st gen caravan has a big advantage for lighter weight alternately. The 2.6L mitsi engined carbureted 4cyl 3spd auto one in less than perfect tune I have gets 20mpg around town - this is better than the best vans sold today. There's no eco-driving it, it's so powerless I can't imagine what you could do to it to drive any slower. The downside is it only gets about 21mpg on the highway because it has to run so fast to keep up, even if I drive slower with it, it was designed for 55mph. I like it for around town when picking up stuff too big for a compact car though as a minitruck alternative. All of the Caravans are known for being exceptionally roomy - probably 2nd in cargo space to only the Astros. I always see contractors recommend the astro first and the caravan second vs all others for this reason.
The Chevy Astros ARE good mileage... for their size/cargo class. You cant stack huge amounts of 4x8 sheet in anything smaller. If you compare them to lighter fullsize vans they are better mileage - for hauling about the same in cargo and towing. If you are only interested in hauling 7-8 people though yes they are among 'the worst' because your comparing to more compact minivans then. That's the wrong comparison - they are a niche vehicle. My future requires me moving 4x8 sheet goods so one is potentially on my future as a good mileage way to do so. Their reliability is almost unreal - 300,000 miles I hear about all the time without any rebuilds or transmission trouble, polar opposite of any 90's or early 2k dodge. The TH700 derived transmission was designed to hold up fine in full size RWD pickups and corvettes behind performance engines so is actually understressed in an Astro, at least as of the early 90's when all early quirks were worked out. Same with the V6 4.3 based off the legendary small block chevy - it's quite powerful for a minivan engine. If i ever had to buy an old van for like $500 and know it would get me to work and back, i'd get an Astro of the early 90's. I wouldn't trust many other makes to be that utterly reliable bought almost blind. Too many cases you can get a caravan, check out everything, have it pass with flying colors and have the transmission dump 5k miles later with only 110,000 on it.
PS - the very first Astros were available with a 4cyl engine and a 5spd stick. It's mileage of 19city/26highway with the iron duke pretty much hangs with some of the best minivans of today, despite having more weight and worse aero. However just like the caravan they were pretty seriously underpowered as well and aren't as well suited for modern 70mph traffic. The reason nobody brags about Astro mileage is everyone has the V6 but at least that keeps up with the traffic. In moderate towing configs the less stressed 4.3 V6 may give better mileage than smaller engines working much harder.
To the Chevy Venture, where does the gear ratio swap come from for a 2.84 gear? That's news to me.
Surprised the Lumina APV/Olds Silhouette/Pontiac Trans Sport wasn't listed. Near as I can tell it had the most aerodynamic figure ever at least for the very first ones - 0.30! That hasn't even been matched TODAY - nothing has even ever touched that, bone stock. They came with a Quad 4 in europe, as well as a diesel, and a stick shift - I think the Getrag 282 used in other Luminas. I would tend to think this ultra aero van, with a Getrag 282, and a 4 cylinder swapped in even an older but unreal-reliable Iron Duke 2.5L (another "easy 300k" engine because it's based off the small block chevy just like the astro v6) would beat any other van here for mileage. While beating them for reliability. While remaining cheap to fix. While not rusting much due to plastic sides. I'm a BIG fan of these vans...
As great as the mileage on Odyssey's and such are, I don't think i'd want one. EXPENSIVE to buy, EXPENSIVE to fix, and most of them require premium gas. Ever price the cost of a replacement 6 speed transmission? A rash of transmission issues affected the accords in mid 2000's, i'm not sure if it's the same for the minivan, but those bit spent $4k for something just past warranty. I'm willing to give up one or two mpg to not have the risk of losing it all on the first mechanical trouble... i'm more impressed by the van doing 19/27 with a older tech 4 speed, than 20/28. If your buying brand new it's fine to throw money at a problem, but you probably don't need the best mileage either. Those buying used or older need to be concerned, plus i'd think if you can do it with an older van... I mean the $30,000 you could spend buys alot of gas. : P
cripplerooster, could you show more info on the 4cyl/5spd swap? I have guesses but i'd like to see specific info, is the one you mentioned the same as what I mentioned? I'm planning something like that in the future, for when moving people is more important than cargo. (will be Astro at first I think)
pete_c - from what I heard the dodge trannies WERENT better in early 2000's, they just changed one set of problems for another. : P
Suggesting the VUE instead of a minivan doesn't make alot of sense, with only 5 seats why not just go with a Saturn SW wagon then and get 29/40? :- /
To a lumina apv mod... i'm not a huge fan of the Ecotec engine. If someone can school me showing it's actually more efficient, okay, but in EVERY CASE so far i've seen the older engines actually get better mileage - Iron Dukes and Saturn 1.9L's for instance. Unless it was all massively increased chassis weight or something... the only thing the Ecotecs seemed to offer was more horsepower, and the potential to handle big horsepower with modifications. I've never seen real good mileage ratings (compared to other 4cyls) from one. Then again it's possible an Iron Duke would be underpowered in a minivan too and a powerful 4cyl would be better than a weaker v6 too..
Hope this is useful to someone..