Full Test: 2007 Dodge Ram 2500 Mega Cab

New diesels don't come around often. In the world of pickup trucks, turbodiesels live such long lives that the arrival of a new! improved! engine to replace a proven one is met with equal parts curiosity and skepticism by diesel loyalists. So it's big news that the heavy-duty 2007 Dodge Ram 2500 has received just such a heart transplant.

We last pitted the Cummins turbodiesel-powered Ram against the Duramax-equipped Chevrolet Silverado and Ford F-350 Power Stroke in June 2006, and the Ram was outgunned. Despite a spacious interior and user-friendly nature, the Dodge's high sticker price and shortcomings in the transmission department helped relegate it to last place.

Dodge introduced powertrain updates for 2007, and all three automakers have, in fact, substantially revised their trucks since just 14 short months ago. The time is ripe for a rematch.

A Hitch in the Plans
We were aiming to test a 2007 Ram 3500 with dual rear wheels, but it turns out that dually Rams are scarcer than straight answers during a presidential debate.

Since the introduction of a new turbodiesel engine is such a rare occurrence, we nevertheless jumped at the opportunity to test the Ram 2500 Laramie Mega Cab 4x4 pickup you see here. Our plans for a reprise of last year's heavy-duty pickup comparison test will have to wait.

Updates to the rest of the Ram have been few since we last visited it, so this test focuses on the new powertrain.

Bigger Numbers and More Gears
An all-new six-speed automatic transmission and substantially new 6.7-liter Cummins turbodiesel inline-6 power plant replace the four-speed automatic and venerable 5.9-liter mill originally created around the time the earth cooled. Nearly 40 percent of the new engine's parts are carried over from the 5.9-liter, and the lifetime of the engine components before a major overhaul is required is said to be 350,000 miles.

Dodge is justifiably boastful that this new turbodiesel already meets 2010 EPA emissions levels. The clean-air approach consists of a single variable-geometry turbo, common-rail fuel injection and a whole lot of exhaust after-treatment — an oxidation catalyst, NOx storage catalyst and particulate filter comprise the Bluetec-brand exhaust tract.

Opting for this diesel over a gasoline-fueled V8 is a $6,100 decision, and it also gets you a heavy-duty ring-and-pinion that's 1 inch larger (11.5-inch versus 10.5-inch), tow hooks, an exhaust brake and a new overhead console for the interior. The new optional six-speed automatic is only $405 more, but the catch is that it requires an additional $995 for the exhaust after-treatment goodies. No one said cleaning the air would be cheap.

Despite its earth-friendly nature, the output of the Cummins diesel doesn't play second fiddle (or third) to its heavy-duty competition. Churning out 350 horsepower at 3,013 rpm and 650 pound-feet of torque at 1,500 rpm, the Ram's oil burner generates 25 hp and 40 lb-ft more than its predecessor. These numbers put it on dead-equal footing with the new Ford PowerStroke V8 and nearly match the output of GM's Duramax (365 hp, 660 lb-ft).

Taking It to the Street
The power delivery of the 6.7-liter engine is smooth and reasonably progressive, and the cabin is never filled with any objectionable noise, even at full throttle. Like the best modern diesels, the Cummins doesn't wear its diesel heart on its sleeve, and that's a compliment. There is scarcely a trace of diesel clatter evident, provided you don't open the door when the engine is idling.

The previous Ram's powertrain really needed a boost in the transmission department, and now it gets one. Two additional gears now make the Dodge more likely to have the right cog for the situation at hand. In theory, the smaller gaps between ratios should translate into smoother shifting, but in practice, the Dodge's gearchanges are delivered with a firmness we don't recall experiencing in the Ford or the Chevy.

A transmission is only as good as its calibration, and we've found that the new six-speed auto is eager to upshift into higher gears during routine driving, a strategy that aims to optimize fuel economy. It is equally un-eager to downshift, so the big Dodge can initially be caught flat-footed when given the spurs for more speed. Pressing the transmission's tow-haul button calls up a calibration that downshifts readily, but because it also holds gears instead of upshifting, it would be overkill for daily driving. On a few occasions, we also observed an inexplicable flat spot in the power delivery following an upshift.

Stout Acceleration
At the track, the Ram swept past 60 mph in 8.5 seconds and covered the quarter-mile in 16.3 seconds at 83.7 mph, a performance that places it in strong standing with other such beasts we've tested.

Scrutinizing the acceleration of workhorses such as pickups might appear a little odd on the surface. It's about more than just bragging rights, though, as in our experience a truck's acceleration provides a solid indication of its ability to cope with heavy loads. The only catch is that this Ram's slimmer body and lighter rear axle will play to its favor when comparing its acceleration numbers against those of the duallies we've tested.

Our usual truck test includes hauling a load up a long grade in the middle of the desert, but in the case of this Ram, we had to forgo this part of our test regimen. Fret not. We'll drag a small house through the desert behind a dually Ram 3500 when we get one.

Tepid Deceleration
Hard braking in the Ram 2500 is uneventful if not effortless — there's always the sense of the 6,593 pounds you're attempting to slow. On the street we found ourselves increasing our following distance while traveling behind other vehicles.

The test results confirm our gut feelings. Braking from 60 mph to zero consumes a fairly long 166 feet, some 17 feet longer than the last heavy-duty Ram we tested. A difference in testing venue for each of the two Dodges might be responsible for a portion of the disparity between their braking performances. The 2008 Ford F-450 Super Duty we tested on the same surface as the 2007 Ram managed to stop in 15 fewer feet, however.

Familiar Wrapper
Heavy-duty trucks sans cargo or trailers make awful daily drivers, since the ride will shake your organs into a froth. Nevertheless, we've observed that the ride quality of such unladen vehicles has gradually become less awful with each truck generation, and the Dodge likewise reflects this trend. And although the Ram doesn't offer the pint-size turning circle of the Ford F-350, its quick steering response produces respectable maneuverability.

Changes to the Ram's interior since our last test are minimal. A button on the dash controls the new exhaust brake, a feature that helps to prevent the conventional brakes from overheating. This promises to be a boon to controlling the Ram's speed while you're towing a trailer down a steep hill.

As before, the Mega Cab's gigantic rear seat makes the presidential accommodations on Air Force One seem snug, and the seats themselves also fold away with ease. The dashboard's simple layout makes for easy use and appears to be constructed to a high standard. A slab of glossy, hopelessly fake wood placed front and center is the primary concession to cheesiness in an interior that continues to work smartly despite being a few years old.

So Far, So Good
The Ram's $57,295 as-tested price is steep, and will separate the casual truck buyer from those who are serious about towing. We'll deliver the final verdict on the 6.7-liter's "Is It Worth It?" factor once we've conducted our towing test.

In the meantime, we can report that the Ram's powertrain updates constitute substantial improvements to its refinement and capability. Hard-core diesel loyalists should take a time out and embrace a brave new world of diesel performance.

The manufacturer provided Edmunds this vehicle for the purposes of evaluation.