Big US monster trucks are about to make a big comeback on Australian roads.

How big is too big? We're about to find out.

The fictional "Canyonero" created by the cartoon TV series The Simpsons is about to come to life.

Full size American pick-ups as wide as a Kenworth truck and more than 6 metres long are poised to return to Australian roads in big numbers, with the appointment of a new factory-backed distributor for Ram vehicles.

US monster trucks were last sold here in mass market numbers in 2007, when Ford Australia imported the F-250 and F-350 that were converted from left-hand-drive to right-hand-drive in Brazil.

Unlike the other half a dozen or so independent operators who convert US vehicles for local roads, the new Australian deal has the backing of Ram Trucks USA.

Although the vehicles are converted to right-hand-drive locally, they come straight off the production line with Australian radios and the Australian navigation system already built-in.

The joint venture between Walkinshaw Automotive Group (which owns Holden Special Vehicles) and veteran vehicle distributor Neville Crichton of Ateco (previously the distributor for such brands as Ferrari, Kia, Suzuki, and Great Wall utes) is called American Special Vehicles.

The biggest differences between ASV Ram vehicles and other locally converted US pick-ups is under the skin.

To find out what it's like to drive, first you must climb aboard.

The ASV Rams are fitted with a moulded dashboard made by the same company that makes the Toyota Camry dash in Australia (rather than fiberglass favoured by other converters), and the right-hand-drive steering assembly is made by the same US company that built the left-hand-drive units. The wiper area covers at the base of the windscreen are made by the same company that makes HSV bumper bars. The list goes on.

The investment in engineering these changes stretches into the millions, and beyond the budgets of other conversion companies.

These key changes are part of the reason the ASV Ram pick-up drives just like it does in the US, and why the company had the confidence to crash test one.

The crash test was done to Australian Design Rules standards (into a barrier at 48km/h) rather than Australasian New Car Assessment Program requirements (64km/h) because ANCAP does not score this category of vehicle.

But it passed the Australian Design Rule test comfortably, and is the only locally-converted vehicle to be crash assessed.

To find out what it's like to drive, first you must climb aboard.

The Ram 2500 sits high off the ground. The side rails aren't only for show, you actually need them to keep your footing as you claw your way to the "captain's chair" driving seat.

The biggest surprise is how quiet the Ram 2500 is. ASV has fitted a new sheet of insulation that replaces the factory insulation (removed during the conversion process) which suppresses much of the noise from the massive 6.7-litre Cummins in-line six-cylinder turbo diesel.

The other surprise is the grunt. Despite weighing 3.5 tonnes, the Ram 2500 accelerates quicker than a Ford Ranger Wildtrak. Then again, 1084Nm of torque will have that effect.

You have better driver's side visibility in a Ford Ranger or a Toyota HiLux than a Ram 2500, even though the Ram needs it more.

The third surprise was fuel economy. After more than 600km of a mix of freeway and city driving, we saw 10L/100km on the open road and averaged 13.5L/100km after some city and suburban driving.

However, we were unladen and didn't use even 1kg of the Ram's 6989kg towing capacity (when fitted with a gooseneck), 4500kg (with 70mm tow ball), or 3500kg (with 50mm tow ball).

The other foible of converted pick-ups that has been addressed: ASV has made new mirror lenses than better suit Australian driving conditions, such as a convex lens on the passenger side for a wider view of the adjacent lanes.

A convex mirror would be welcome on the driver's side but Australia's outdated ADR requirements don't yet allow it in the Ram truck category. This means you have better driver's side visibility in a Ford Ranger or a Toyota HiLux than a Ram 2500, even though the Ram needs it more. Hopefully, common sense will prevail and this rule will change or an exemption can be made by the authorities.

Other downsides? There aren't many. The column shift gear lever is on the right of the steering wheel, which makes it close to the door (no hardship, I was used to it after a day) and the foot-operated park is on the right (another habit quickly adopted).

Overall, though, the positives outweigh the few negatives. It's the closest a local conversion has ever been to a factory finish, both in interior presentation, functionality and the way the vehicle drives.

Having the backing of a warranty from the factory and the conversion work being validated by a crash test also adds peace of mind.

It aint cheap, though, at roughly twice the US price before currency and steering conversions. Then again, it's not much dearer than a top-line Toyota LandCruiser, which can "only" tow 3500kg.