Isuzu D-Max 2024 review: 4x2 SX Crew Cab Chassis (1.9L) High Ride long-term | Part 2

Our 4x2 D-Max dual cab-chassis, with 1.9-litre turbo-diesel, has a payload rating that’s 80kg higher than its 3.0-litre equivalent. That may seem illogical, given that the 3.0-litre engine has 30kW more power and 100Nm more torque.

However, it all comes down to tare weights, or what these vehicles weigh in bare cab-chassis form with no trays and with only minimal fuel in their tanks.

Fact is, the 1.9-litre drivetrain is 80kg lighter than the 3.0-litre version, so that means the 1.9 can legally carry 80kg more than the 3.0, given they share the same 3000kg GVM rating.

In this case, after deducting the combined weight of our test vehicle’s aluminium tray (119kg), tow-bar kit (47kg) and rubber mats (5.0kg) from its 1255kg payload rating, that leaves 1084kg of payload capacity compared to 1004kg for a 3.0-litre equivalent.

So, this month it was time to put this theoretical advantage to the test, by loading it up with more than one tonne of payload and hitting the road.

We wanted to see how the smaller engine responded to heavy loads that could be carried by hard-working tradies, farmers, road crews etc.

Your on-tray sir

The 119kg general-purpose aluminium tray is relatively light, given it’s about half the weight of a full-steel version. That’s significant if big payloads are important to you, because every kilogram of tray weight reduces your vehicle’s payload by the same amount.

According to our tape measure, the tray’s load floor is 1800mm long and 1777mm wide with drop-sides that stand 250mm tall.

The 119kg general-purpose aluminium tray is relatively light, given it’s about half the weight of a full-steel version. (Image: Mark Oastler)

It has a sturdy bulkhead frame, with stout mesh protection for the rear window. There’s also a choice of 12 internal load-anchorage points, or two rope rails along each side for external securing of loads.

Given our test vehicle has covered more than 7000km, this tray and its fixtures are still pleasantly free of squeaks and rattles. And being made of aluminium ensures it remains rust-free, so it’s a good all-rounder in this application.

Loaded to the (D) max

We inflated the tyres to the recommended pressures and secured 950kg in the tray, which combined with driver (me) resulted in a 1040kg payload that was only about 40kg under the 1.9’s legal limit.

The heavy-duty rear suspension that’s unique to D-Max cab-chassis models was up to the task, with its leaf springs only compressing about 40mm.

That left about 60mm of bump-stop clearance, which was ample in ensuring there was no bottoming-out during our load run.

As expected, the relatively harsh unladen ride quality became much smoother with such a big load to engage its rear springs. These workhorses shine when carrying heavy loads like this, given that’s what they are primarily designed to do.

We inflated the tyres to the recommended pressures and secured 950kg in the tray. (Image: Mark Oastler)

In terms of chassis performance, the D-Max didn’t feel like it was significantly affected by this load. The higher centre of gravity it created was noticeable during cornering, but when driven at sensible speeds on a variety of roads it remained stable and sure-footed. Steering response and braking were largely unaffected.

The 1.9-litre turbo-diesel belied its relatively small displacement, competently hauling this weight with the most noticeable difference being more accelerator pedal required to maintain its performance.

Even so, the 1.9’s shorter diff gearing allows this engine to operate at the slightly higher rpm needed to operate in its peak torque zone, so it moved this load quite efficiently, particularly from standing starts.

We trialled sequential manual-shifting for comparison, but found the Aisin six-speed auto was efficient if left in self-shifting mode.

It was also during our highway driving test that we saw average consumption on the dash display drop to 10.7L/100km with more than one tonne on board. (Image: Mark Oastler)

The engine’s highway performance was also low-stressed, requiring a leisurely 1800rpm to maintain 110km/h using the adaptive cruise control.

The six-speed auto seemed a bit confused at one stage, hunting between fifth and fourth gears several times before settling down.

It was also during our highway driving test that we saw average consumption on the dash display drop to 10.7L/100km with more than one tonne on board.

We have no doubt it would have continued dropping with more highway use. Our experience with D-Max turbo-diesels, in combination with the auto’s full torque converter lock-up on third, fourth, fifth and sixth gears, is that they produce excellent economy during long highway hauls.

While it has less power and torque than the 3.0-litre, its lighter tare weight, broad spread of torque and shorter gearing ensures it gives little away to its more powerful sibling under heavy loads. (Image: Mark Oastler)

Tyre and engine noise were pleasantly low at these speeds, with most noise intrusion being some mild wind-buffeting around the bulkhead and mirrors.  

The toughest test was our 13 per cent gradient, 2.0km-long set climb at 60km/h. It shifted down to third gear and 2400rpm, which was within its peak torque band between 1800-2600rpm.

With two lower gears in reserve and ample accelerator pedal travel remaining, it hauled this load to the summit with commendable ease.

Engine-braking on the way down, in a manually-selected second gear, was not as strong but in our experience typical of small displacement turbo-diesels trying to restrain heavy payloads on overrun. In others words, they're great at going up hills, but not so great at going down.

Even so, the front disc/rear drum brakes comfortably took up the slack, with a few firm applications keeping the road speed below the posted 60km/h limit.

Overall, the 1.9-litre performed beyond expectations with a one-tonne-plus payload. While it has less power and torque than the 3.0-litre, its lighter tare weight, broad spread of torque and shorter gearing ensures it gives little away to its more powerful sibling under heavy loads.

Fuel consumption

We added another 649km to the odometer this month, which like the first month was comprised mostly of city and suburban driving with some highway running.

It’s been mostly unladen, apart from our payload test which was a 112km mix of suburban and highway driving.

When we refuelled the 76-litre tank, this time the dash display was claiming average consumption of 11.1L/100km, which was slightly higher than the 10.6 it claimed last month and further north of Isuzu’s official figure of 7.0/100km.

It’s been mostly unladen, apart from our payload test which was a 112km mix of suburban and highway driving.

However, our own figure calculated from fuel bowser and trip meter readings, headed in the other direction down to 9.1 which is lower than the 9.7 recorded last month.

So, that’s good news in terms of fuel economy, even though there appears to be a growing discrepancy between the D-Max’s onboard calculations and our own.  

Even so, we’re happy to stand by our at-pump numbers as they reflect the ‘real world’ ownership experience. And given that it’s now knocking on the door of consumption in the 8.0L/100km zone, the 1.9 is proving to be increasingly economical regardless of what task we throw at it.

Coming up…

We have some more heavy load-hauling planned for our final month with the 1.9, so stay tuned.

Acquired: August 2023

Distance travelled this month: 649km

Odometer: 7660km

Average fuel consumption (at pump): 9.1L/100km