Slow and Steady - 2014 Ram 1500 EcoDiesel Long-Term Road Test

Edmunds.com

Slow and Steady - 2014 Ram 1500 EcoDiesel Long-Term Road Test

Thanks to the 2014 Ram 1500 pickup's onboard computer, drivers know exactly how long they've been sitting in traffic.

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emajor

Good gawd. Condolences, Kelly. I start to lose my patience in about 10 minutes of stop-and-go.

Between the traffic and real estate prices it sounds like SoCal has enough daily stress to completely eclipse the nice weather and coastline. Assuming you can ever get to the coastline at 21 mph.

5vzfe

I hate traffic. IMO the whole point of having a car is for convenience - i.e. faster traveling. Driving to my parents house from where I'm living is 108 miles, and it only takes about 90-115 minutes on I-5. A little less if you drive above the speed limit. The drive is so monotonous and boring that it seems much longer though. I would go absolutely crazy living in Los Angeles and sitting in traffic for 5 hours total in one day. I've been to SoCal once for vacation, and I don't think I could live down there. Kudos to you for being a much tougher and patient person than I am.

bankerdanny

My 25 mile one-way trip this morning from the north side of Chicago to the South Side took about 1:15, so I am sympathetic. And my much smaller 2002 Saab 9-3 SE probably averaged about the same MPG.

carguydaryl

Sorry about the commute... SoCal Traffic surely sucks. But 22.3 mpg is friggin impressive.

daryleason

I'm about to post something in this comment that y'all are going to read and think "He's an idiot." But follow along with me on this one. Fuel economy calculations can frustrate me sometimes. I know that the further away you get from a 1:1 ratio for gearing, the better your fuel economy gets. In other words, if First Gear is 1.2 : 1, and Fifth Gear is .075 : 1, your fuel economy is better in fifth than first, assuming, of course, that the engine RPMs are exactly the same. How...here's where I end up with something I can't quite wrap my head around. I've been trying to understand WHY it doesn't work for years. It's got to do with Tire Sizing. The 2012 Jeep Wrangler that Edmunds owned showed that the reasoning doesn't work.

So my thought is this...if you go to a larger diameter tire, the circumference is larger. This means you travel a longer distance than the you would with the stock tire, per revolution. So if you have a stock tire that travels 100 inches, per revolution, then go to a larger tire that travels 115 inches, per revolution, you are getting a greater distance with the same RPM, an increase of 15%. You would think this would equate to a higher MPG (fuel economy) due to a drop in engine RPM or the same MPG (fuel economy) at a higher speed. However, real world data does not support this.

Anyone willing to bite the bullet and help me understand why?

tlangness

Requires more power to move more mass. A bigger tire (with all else being equal, rolling resistance, weight, width etc.) will require more force to move one revolution. The same way it would take a hamster more steps to rotate a larger wheel in his cage.

daryleason

@tlangness : and that's where I still get hung up. So I get the more mass. But the mass increase can't be that much. We're literally talking a volume that's comprised mainly of air. With the hamster analogy, which I appreciate, that would be more akin to putting a smaller tire on a vehicle, since it'd take more revolutions to go the same distance as the stock tire, assuming you are equating revolutions to steps.

colorado kid

@daryleason: A couple things. 1)Yes the larger tire diameter results in more distance covered per tire revolution , and thus more distance covered per engine revolution, just like being in a slightly higher gear, but the same power is required to to the same work in the same time, so something else changes - the throttle is farther open so each combustion event is a little bigger - with gearing the reduced friction of lower RPM more than makes up for the bigger (but less frequent) combustion events - with larger tires there is increased friction from pushing a larger tire thru the air, and raising the whole vehicle by half the diameter increase exposes more air to the messy underside of the vehicle. 2) Unless you tell them, the devices used to measure speed and distance don't know there are bigger tires - the speedometer shows the same vehicle speed for the same wheel RPM, even though it is now traveling faster (thus more aerodynamic drag) and the same distance per wheel revolution is recorded by the odometer even though the vehicle is traveling farther - so the math for fuel economy is messed up. Using your example numbers the vehicle would travel 115 miles while recording 100 mile on the odometer, so figuring its fuel efficiency you would divide 100 miles by the gallons used, but you should be starting with 115 miles to get correct mpg.

5vzfe

That small difference in mass adds up over time. This isn't really a good example but here's my experience with two tires of similar circumference: I plus sized the wheels on my 4Runner from 265/75 R16 to 265/70 R17. The rims are both aluminum alloy and are both OEM - but from two different years (2002 vs 2015). The old 16 inch tires are michelin latitude green x something - basically highway tires meant to promote efficiency through low rolling resistance. The 17 inch tires (remember both have the same or very similar total diameter, just the center "doughnut hole" where the wheel sits are different sizes) are Toyo All-terrains. While overall there is less area on the sidewalls on the 17s, these tires are much much denser than the michelins, and this is by design - they need to be stronger for dealing with different surfaces, and to make up for the lack of shock absorbing sidewall material. With the michelin tires I could let off the gas and coast for what seemed like entire blocks around town - not so with the Toyos, it felt like I was dropping an anchor each time before I got used to them. Since the engine has to work harder to rotate these new heavier tires, I did see a decrease in gas mileage about 1-2 mpg on the highway, overall averages are about the same though maybe .5 mpg lower. There is almost a comical difference in weight between the two setups, I switched back to the michelins very briefly and put them on myself in the driveway and they felt super light compared to the Toyos.

longtimelurker

daryleason said:

@tlangness : and that's where I still get hung up. So I get the more mass. But the mass increase can't be that much. We're literally talking a volume that's comprised mainly of air. With the hamster analogy, which I appreciate, that would be more akin to putting a smaller tire on a vehicle, since it'd take more revolutions to go the same distance as the stock tire, assuming you are equating revolutions to steps.

There is more rotational inertia, yeah - but the main thing is that instead of moving the vehicle 100 inches, it's having to move it 115 inches. That takes more power - more "work." So it takes more BTUs to do it. It's not just a fixed RPM-X-equals-X-fuel deal - it takes more fuel to maintain that engine rpm when you have a higher (numerically lower) effective gearing...which is what you have with larger tires.

daryleason

@longtimelurker
@tlangness
@5vzfe
@whoever else is trying to help me:
Thanks for the help guys. It's like I said...I KNOW it doesn't work the way I said in my mind I feel it should work. Some day, when I am ultra rich and can burn money faster than the Federal Government [non-permissible content removed] I'm going to buy two identical vehicles and start playing around with it until I can understand it by visual comparisons. I told y'all y'all would read the posts and think "what an idiot." It's one of those things that you know, but you keep trying to disprove yourself on.

bankerdanny

Do you own a bicycle Dary? What happens when you are riding and you transition from a flat road to an uphill incline? If you don't (or can't) change gears to a lower one, you have to push harder to maintain the same cadence (pedal RPM).

It's the same thing here. Adding bigger diameter tires is just like going up a hill; to maintain a given RPM in any gear the engine requires more power. More power requires more fuel.

Poor aerodynamics has the same effect, it take more power to push through the air, more power = more fuel.

Pretty much anything that requires an engine to use additional force to maintain a given speed in a given gear will reduce fuel economy.

daryleason

@bankerdanny : That was the best visual representation I've received so far. Thank you very much.

misterfusion

Regarding traffic: Even here in L.A., it is very much a choice. Like many of you, I refuse to deal with a very long commute; it is an important quality-of-life issue for me. So, I choose to live closer to where I work. I choose not to purchase a 4000sf house in a distant suburb. Obviously, if one's priority is the 4000sf house (of which 3000sf is probably not used 90% of the time), then a horrific commute will be the price one pays.

allthingshonda

Although I think fuel economy is important (like for my 90 mile round trip commute) it should be in context with the vehicle application. If I buy a truck I want it to have decent fuel economy but more importantly I need it to be able to work. The EcoDiesel gets the best fuel economy out of any full size or even mid size truck (except for the new 4 cylinder diesel in the GM twins) but it sacrifices quite a bit of capability. Most people would rightly say that the EcoDiesel is more than capable for what most people use a truck for but that's not the point. A Chevy Colorado has more towing capability than this truck; a $50,000 full size truck should not have less capability than a smaller cheaper truck. It's like losing a drag race in a Dodge Charger SRT8 to a Ford Focus ST.

GM is way behind Ford and even Ram with innovative powertrains for their trucks but that ancient 5.3 pushrod V8 and 6 speed auto seems to be the best compromise for fuel economy and power. It doesn't pull as hard as the Ecoboost engines and doesn't get the fuel mileage of the EcoDiesel but it's in that sweet spot in the middle of both. If I was buying a Ram I would get the 5.7 Hemi with the 8-speed auto. Real world fuel economy and capability is about the same as Ford's EcoBoost engines and it's cheaper to buy and maintain than the EcoDiesel.

skyim73

allthingshonda: I think your "that's not the point" about capability vs, say, a Colorado, fails to take into account the fact that sheer towing numbers aren't the only measure of capability. For you, towing is the priority judging by your post. For me, while a V-6 Colorado or Canyon would tow my 5000 lb folding trailer just fine, I want really good long haul towing fuel economy, something at which diesels excel. I also go to high elevations a lot and like having the partial altitude compensation a boosted engine provides. For that reason, I've looked at the 2.8 Duramax in the GM twins, but the truck falls short in another vital area for me - cab accommodations. I want to be able to bring another couple along on some trips. The rear seat and total cab volume of the crew cab Colorado/Canyon just won't do that job for me,. So they lack that particular capability for my application, and in my calculus that trumps the appeal of a smaller, handier truck.

Not convinced that there is going to be all that huge a cost delta since the GM dealers seem to be planning to hold MSRP on the little diesels (and they easily crack 40k) while careful shopping can yield pretty substantial discounts on the Rams. If you don't need to have leather or nav, a low to mid forties sale price on a reasonably equipped CC 4x4 is in reach, with the difference of perhaps a few grand representing tangible value in the form of that roomy cab and a wider cargo bed for me. An Ecoboost F-150 has the cab and the towing, too, but every test I have seen indicates that the V6 EB engines are more boost than Eco, so the Ford fails my fuel economy metric... and yeah, I know all the diesel cost arguments, but here in SoCal diesel is cheaper than regular and has been for some time. I understand that this varies, but the tradeoffs work for me since I value the torque and altitude performance of the diesels.

The Ram 1500 with the 3.0 fills the bill for me, though I REALLY wish you could get a locking differential on the Ram. I spend some time on soft dirt tracks leading to pretty places and a limited slip isn't much help in those conditions compared to a true locker. That's a demerit for the Ram vs all the other candidates I am considering. I also wish they were quicker, but most of my use will be long range trips and I have learned to curb my inner racer as the years have passed. Also, after test driving, they feel quicker than they are because they come off the line briskly with all that low end torque, so they don't feel quite as sluggy as the numbers seem to indicate. In the overall tradeoff study, I think the Ram 1500 Ecodiesel gives me the best balance of my capability needs, and I'm probably going to get one later this year.

Different tools for different jobs. We each define our personal needs and inevitably these wind up giving us different personal decision algorithms, right? I think we may be seeing a bit of a golden age with the current crop of light duty pickups - I fear the more stringent CAFE regs on the horizon are going to start to narrow the choices available to us very soon. I'm jazzed to have as many good options as we see right now, and this finally looks like the year to jump on my downsized tow vehicle and retire my old faithful 3/4 ton gas hog.

Big thanks to Edmunds for extending this road test, BTW. I keep my trucks a LONG time and hugely appreciate a longer view!