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CyberEric
CyberEric Dork
7/30/20 7:23 p.m.

I was looking at diesels (not just trucks) in my area as I am interested in going to biodiesel (probably need to make a separate thread on that), and came across a Nissan/Datsun small truck that the owner claimed got 40 mpg! Can anyone confirm? Think it was an ‘83. Never knew about them.

Got me thinking, what is the best one could expect to get from a truck? And when I ay truck, I mean anything with a bed, as in VW Caddy.

It’d be great to have something that I could commute in that I could also haul in.

Stealthtercel
Stealthtercel Dork
7/30/20 8:06 p.m.

Well, commuting would be an issue and hauling (in either sense) would have obvious limitations, but I bet the mpg from one of these would be hard to beat: 2CV pickups for the Royal Marines . 

amg_rx7 (Forum Supporter)
amg_rx7 (Forum Supporter) SuperDork
7/30/20 8:14 p.m.

Does the ability to accelerate or keep up with traffic matter?

Cuz that vw won’t :)

CyberEric
CyberEric Dork
7/30/20 8:23 p.m.

I love me some 2CV. It's also my wife's dream car. 

Hard to come by around here. 

Hehe, are the VW Caddy's that slow?

No Time
No Time Dork
7/30/20 8:42 p.m.

I had an early 80s S10 with an Isuzu diesel.

Fuel economy was great, but you could hold your foot to the floor on the Wilbur Cross/Merritt Pkwy all the way from New Haven, CT to the merge with the Hutch in NY. 

It would drop to 40-45 on the uphills and reach about 75 on the way down the other side. 

ultraclyde (Forum Supporter)
ultraclyde (Forum Supporter) UltimaDork
7/30/20 8:58 p.m.

96 2wd F250 powerstroke I had managed a calculated 30mpg on one tank. But that may not be what you're looking for. Also, it got much worse in town. 

STM317
STM317 UberDork
7/31/20 6:13 a.m.

Some 80s Ford Rangers had optional diesels, but they're not super common.

Cactus
Cactus HalfDork
7/31/20 7:15 a.m.

I think a Japanese kei truck would give anything a run for its money. Though most of them have real short gearing, so maybe not. And I think they're all gas.

Fueled by Caffeine
Fueled by Caffeine MegaDork
7/31/20 7:24 a.m.

Those old 80's truck diesels are cool, but man will they have a hard time outrunning a bicycle..

Saron81
Saron81 HalfDork
7/31/20 7:28 a.m.

bobzilla
bobzilla MegaDork
7/31/20 7:44 a.m.

I can confirm that the Isuzu P'up's from the early 80's were good for 42mpg around town and 40 at highway speeds

Mom and Dad had one that I spent a lot of time in the bed with an aluminum camper shell. Went through a hail storm south of the grand canyon that may have led to my hearing impairment now. That and loud cars, bikes and tens of thousands of rounds shot without hearing protection. and 25 years of mowing. 

Dave M (Forum Supporter)
Dave M (Forum Supporter) HalfDork
7/31/20 7:45 a.m.

I mean, a Colorado diesel gets close to 30 mpg on the highway no? 

Above that, you're either (1) hybrid in town or (2) aero on the highway.  There's no super-efficient hybrid truck yet for around town, and trucks are by definition not very aero. So, 30 is pretty darn good.

So yeah, it's gotta be made of cardboard and have a lawnmower engine. 

Fueled by Caffeine
Fueled by Caffeine MegaDork
7/31/20 7:50 a.m.
Fueled by Caffeine
Fueled by Caffeine MegaDork
7/31/20 7:53 a.m.
STM317
STM317 UberDork
7/31/20 8:02 a.m.
Dave M (Forum Supporter) said:

I mean, a Colorado diesel gets close to 30 mpg on the highway no? 

Above that, you're either (1) hybrid in town or (2) aero on the highway.  There's no super-efficient hybrid truck yet for around town, and trucks are by definition not very aero. So, 30 is pretty darn good.

So yeah, it's gotta be made of cardboard and have a lawnmower engine. 

01-12 Ford Rangers with the 2.3 Duratec/manual trans combo can see 30mpg highway pretty easily. They run on regular unleaded instead of diesel, and they don't cost $35k like a new Colorado or Ram EcoDiesel. They're not race cars, but they get by pretty well with the Duratec when you can row your own.

I'm confident that with some minor aero work like a grill block and underbody tray and maybe a sixth gear to reduce rpms on the highway I could've gotten mine into the mid 30s or better.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) GRM+ Memberand MegaDork
7/31/20 9:53 a.m.

Older diesel pickups like the Nissan, S10, Ranger, Caddy, were based on one thing - MPG.  A Rabbit Caddy diesel has something like 70 hp.  None of them will perform well enough to really be a highway vehicle, especially if you're hauling 500 lbs worth of stuff.  Some might be easily souped up, but old diesel tech is just that... old.

Modern turbo diesels (think at least direct injected, but common rail is better) are what you will likely need.  The newer Dodge V6 Ecodiesel and the Colorado/Canyon diesels are made by VM Motori and have all the modern bits.

There is a relatively inexpensive kit to drop a 1.9L TDI into Rangers, but it's not quite as simple as a drop-in.  I believe it converts the bellhousing pattern to GM, so most of the Ranger conversions use a NV3550 which is a pretty simple swap.  The TDI in stock form isn't much to talk about, but they can easily be turned up to 11 and make decent power in the Ranger.  Many of the TDI swap guys are claiming 35+ mpg.

Your choices for factory diesel small pickups are limited.  They'll mostly be 80s stuff that is about as wimpy as you can get, or modern, post-2008 DPF/Urea complex things.   You should be able to find a Colorado/Canyon that works.  They at least get the 2.5L (I think) VM which has the ability to be tuned for more efficiency and a little more power.

morello159
morello159 Reader
7/31/20 10:12 a.m.

Surprised nobody has mentioned the F150 diesel. 33mpg in the real world - check it out.

https://www.thedrive.com/new-cars/21396/2018-ford-f-150-diesel-truck-review-how-does-850-miles-of-range-on-a-tank-sound

buzzboy
buzzboy Dork
7/31/20 10:36 a.m.

Our P'Up pulled a solid 45mpg city. Sadly it became one with the earth still running like a champ.

sleepyhead the buffalo
sleepyhead the buffalo GRM+ Memberand Mod Squad
7/31/20 10:51 a.m.
bobzilla
bobzilla MegaDork
7/31/20 11:42 a.m.
buzzboy said:

Our P'Up pulled a solid 45mpg city. Sadly it became one with the earth still running like a champ.

yes, Toyota bought their taco frames from Isuzu. Most rusted in two around us while the drivetrain lasted forever.

CyberEric
CyberEric Dork
7/31/20 12:00 p.m.

Haha! 

Wow, the Rampage! Had no idea they were that efficient. Very hard to find though.

Same with the Isuzu, but I see them very occasionally. 45 City? Damn! Seems like the winner.

The diesel F150 is too expensive, but good to know.

Ranger is probably the sweet spot.

 

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) GRM+ Memberand MegaDork
7/31/20 12:17 p.m.

I'm a bit jaded being from the repair side of things, but new diesels are WAY too complex for me to want one.  Miles of wires, hundreds of sensors, cooled EGRs, particulate filters, hydroscilators and confabulators.... Not to mention they are about $30k too expensive for my wallet.

For me the sweet spot is post-CRD, but pre DPF.  Pretty much 2002-2008.

CyberEric
CyberEric Dork
7/31/20 2:00 p.m.

Curtis, do you mean VWs of that era or any diesel of that era?

I agree, the complexity makes me very nervous.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) GRM+ Memberand MegaDork
7/31/20 2:25 p.m.

Any diesel.

In the 70s, Diesel meant 2-stroke Detroits in buses and 18 wheelers.
In the 80s, it meant Oldsmobile 350s that blew head gaskets
In the 90s, it at least meant reliable diesels that made some decent power, as long as it was a behomoth 1-ton truck.
2000's really started to see some cool stuff - direct injection, common rail, VNTs.  Then 2008 EPA regs came along and you had to inject urea into a fancy filter, have specially cooled EGRs, etc, and it got weird.

My dream diesel is an 05-07 Duramax.  All the good stuff, none of the crazy stuff.

If you're just shooting for an MPG truck that can haul some stuff, I'd look for a Colorado/Canyon with the VM Motori.  If you need a mid-size truck that works hard (towing, good power, tire smoke) you might be disappointed, but they will get good MPG.

I'm trying to find a decent diesel to swap into my Mazda B4000 and it's tough.  The 1.9 TDI would work except that I tow and haul a lot, and it just wouldn't make the oomph I need.  I'm thinking maybe the 3.0L V6 Motori from a Cherokee, but I'll have to find a way to delete all the extra fancy stuff.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) GRM+ Memberand MegaDork
7/31/20 2:34 p.m.

With most diesels, they are tuned conservatively for two main reasons: NOx emissions and quiet operation.  The big thing they do is keep injection timing a little behind optimal.  This reduces cylinder pressure to keep NOx well below where it needs to be and also keeps things quiet and smooth.  Bumping up the timing with a bit more advance can still keep NOx below the legal level, but make more torque and help MPG significantly.  You might be able to find a tuner box that will let you DIY that parameter.

Given diesels' factory tune, there is significant power AND mpg that can be found with adding a bit more timing and a bit more fuel.  The name of the game with making gas engines efficient usually means less fuel and less power.  Getting more power from an NA gas car means cam and airflow which increases overlap and kills mpg.  With a diesel, there is often zero valve overlap.  All of the power comes from turbo and fuel.  Add more fuel, it adds more boost.  Therefore (assuming you are driving in the same style as before) adding fueling and timing advance on a diesel will often add hp, tq AND mpg at the same time because it effectively increases cylinder pressures and therefore extracts more BTUs from the fuel you are injecting.  More btus out of the fuel means you consume less.  Typical OTC tuners on electronic diesels can add 20-30% more hp and 10% more mpg.

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