Lake style wheel covers with narrow (215 or 225 )LT highway tires at max pressure would gain as much MPG as the roller rockers.
A good intake system, good mandrel bent exhaust, synthetic rear diff lube and ATF, plus stay away from ethanol fuels.

I have a friend who installed a 6.9 International diesel (IDI) in a Ford bronco, and another one in an F150 for his son. Both get 30 mpg on the highway. But it wasn't cheap, nor easy.

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1982 300SD " Wotan" ..On the road as of Jan 8, 2007 with Historic Tags

I think that's your solution right there-just make everybody chip in for gas and you're all set.

For several months earlier this year I had a paying passenger for my commute. His car was sufficiently decrepit that he didn't trust it to drive to work, and he lived about 100 yards out of my way, so I ended up getting paid ten bucks a week for going someplace I needed to go anyway.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.

It's not a dream, so much as work most people aren't willing to do. It's hard enough to get people off their own couch, much less get them to drop in taller gearing via changes in the rear-end/trans, fabricate an aerodynamic bed cover, do some other aero mods, etc, etc... Well, that and the way a lot of guys think about their truck, you'd think it was their purse.

A lot of the conventional wisdom simply doesn't work in practice. Great in theory, makes perfect sense, until you throw mother nature into the mix.

I got an increase (slight) in mileage by going to lower gearing in my camper van. The 4.10 gears make cruising up hills in third gear easy work for the engine and it stays near the peak of the torque curve when torque is needed. Still cruises in OD nicely.

Throw a big box like a van into the wind and efficiency left about a quarter 'til three yesterday.

A lot of people lie (some innocently) about their mileage. Some of those are selling you something. Over the years I have seen a few vehicles that perform beyond reason for what they are. They are rare.

Car MPG Efficiency Modifications Main - EcoModder

It's fun to check this stuff out but good luck getting any of it to pay off. Big vehicles need big brakes and tires to stop and lots of gas to go. If you can reduce the amount of gas to make it go you should be able to reduce the amount of brakes to make it stop, no?

#1 gas saving modification: Live close to where you work. Don't give your money to scumbag oil companies or scumbag real estate developers.

#2 Don't drive within ten miles of a Wal-Mart.

I see how #1 works, but what about #2?

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.

You wouldn't swap in lighter duty brakes, you'd swap for a lighter duty vehicle.

One of many counterpoints is when work is driving the van.

It's getting more difficult to not live within ten mile of Walmart. Even if you don't move, Walmart closes in.

Sixto
87 300D

I would have to drive about nine miles to be ten miles from the nearest Wal Mart, and that only works if I head east. Headed north, by the time I'm ten miles from the north Carson store, I'm getting close to one of several in Reno. Heading south, I go five miles toward the south Carson store before I start getting farther away, and you have to go down almost to that Wal Mart to take U.S. 50 over the hill to go west.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.

It does depend on the population density. I have 3 Wally Marts within 10 miles.

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1982 300SD " Wotan" ..On the road as of Jan 8, 2007 with Historic Tags

I suspect the poster who said less brakes meant coast more brake less, as a driving style.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Possibly, but here's more of the quotation -

Sixto
87 300D

Not equivalent, I think.
Slow acceleration reduces gas consumption.
Slow braking WOULD reduce the amount of energy turned into heat (waste), but do you really want to be in a vehicle that cannot stop as quickly as you want it to?
Reducing the weight of the vehicle helps acceleration, economy AND braking. But we are talking about a specific vehicle--difficult to reduce the weight very much.

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1982 300SD " Wotan" ..On the road as of Jan 8, 2007 with Historic Tags

the point is not to reduce the size of the brakes.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.