Do you need a V6 diesel ute for heavy towing?

 

Is the performance of the V6 diesel utes - VW Amarok and Merc X-Class sufficient to justify the sky-high pricing - and do you really need that?

 
 
 
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Big misconception among the towing fraternity: torque is not what delivers performance. It’s just not.

Torque is a building block of power. See more on this at How Stuff Works >>

Power = torque x revs (if you get the units right). Diesels make a lot of low-rpm power, which makes them great for towing.

(Because you don’t have to rev their tits off to deliver a decent amount of power to get the job done.)

The 3.2-litre diesel in the BT-50 makes maximum torque of 470 Newton-metres from 1750-2500rpm.

470 Newton-metres at 1750 is not the same thing as 470 Newton-metres at 2500.

It’s 86 kilowatts at 1750rpm, and 123 kilowatts at 2500. So the performance is going to be significantly better at 2500rpm compared with 1750, even though the torque is the same.

Let’s say you’re at a particular speed on a hill. You can be in fourth gear at 1750 or third at 2500. Go for third if you need additional performance at that speed. Because that’s how this works.

Peak power is 147 kilowatts at 3000rpm. The performance is going to be better again at 3000rpm, because the power is greater, even though the torque is actually less. So on the same hill, at the same speed, second at 3000rpm is the winner.

See also:

The other point that’s important is that these peak numbers only happen at wide-open throttle.

You have to be in the right gear, needle on 3000, right foot nailed to the floor - and then, if you are maintaining revs, you have sufficient power to get the job done.

And if not, you’ll have to let the speed drop and choose a lower gear at 3000.

If you are accelerating in these conditions, you have more than adequate power to get the job done.

Let’s talk about upgrading: The X-Class has a decent engine with very linear power delivery from 1400 to 3200 rpm.

Compared with the BT-50 it’ll offer 20-25 per cent more performance across the same sort of rev range, with the throttle nailed.

You are definitely going to pay for that - it’s going to be $75,000 plus on-roads, and more like $100k if you play ‘options bingo’.

Unfortunately, like the Nissan Navara from which it is cloned, X-Class has a coil-sprung multi-link rear suspension setup that’s poor at heavy towing or loaded dynamic performance generally.

Mercedes-Benz product support is also terrible.

The V6 Amarok: $12k less. And you get a leaf-sprung rear, which is ideal for heavy towing. But Volkswagen reliability remains poor, and support is among the worst in the car industry.

You’ll get 165 kilowatts maximum. That’s 12 per cent more peak power. But you have to rev it to 4500rpm to get it there, and that’s just undignified.

Diesel engines do not enjoy 4500 revs, and you will not enjoy driving it in this way. It’s difficult to do.

Also, I just downloaded the latest Amarok brochure. Which you might do, if you are in the market. They claim 550 Newton-metres from 1500-2500. (That’s believable.)

Unfortunately, they also claim 165 kilowatts from 2500 to 4500 - and that’s just bullshit. Total bullshit.

See it for yourself here >>

As in, it is a bare-faced lie about the performance of that engine. And by ‘lie’ I mean a false claim about what is physically possible, subject to that torque spec being correct.

As any first year engineering student on earth would confirm.

550 Newton-metres at 2500 rpm equals 144 kilowatts - because that’s how the Newtonian universe operates. It’s certainly not the 165 kilowatts Volkswagen claims at those revs, and you can’t have both.

Engine performance is so critical to the vehicle purchase decision, and not everyone is technically illiterate. So in my view, this is deceptive and misleading conduct from them, again.

It could be an honest error, but we are discussing the global leader in deceptive and misleading conduct when it comes to engines.

If there’s one message you should take away from this report, it’s this: Unless you are currently extracting the maximum performance from your vehicle, drive differently. Change back.

This is the easiest, cheapest way to derive additional towing performance. Exploit peak power if necessary.

Upgrading is expensive. You probably don’t need to, because there are very few three-tonne towing problems that cannot be solved with 147 kilowatts at 3000rpm.

‘Upgrading’ (if that’s the right word) to a Volkswagen or Merc could easily prove to be a major downgrade in support - especially in remote areas.

These two brands have grunty utes, but they are specialists at treating consumer law as if it is optional, and treating you like you simply don’t matter, right from the instant they cash your cheque.

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