The upcoming, Mercedes-Benz G-Wagen will launch with the top-spec Mercedes-AMG G63 when it arrives in Australia.

With production for Australia set to begin in April–June, the 2018 AMG G-Wagen will arrive in Aussie showrooms around June-July, followed by the G350 diesel later in the year.

The upcoming G63 is expected to make use of the same 4.0-litre V8 twin-turbo engine found other AMG variants, however its state of tune remains unclear.

The engine has a range of potential outputs, running from 350kW to around 450kW. It's likely the G63 will adopt one of the 'less powerful' tunes.

Above: The AMG M178 V8 features across the current range 

As it stands today, the 'Professional' G-Wagen (G300) makes up for 80 percent of annual sales. Of passenger versions sold, the G63 makes up around 85 per cent, with the G350 accounting for the remainder.

It's still unclear whether Mercedes-Benz will use its new diesel inline-six in the upcoming G350, or stick with the current engine for the foreseeable future.

Speaking to CarAdvice, head of communication for Mercedes-Benz Australia, David McCarthy, said a decision on diesel engines isn't confirmed.

According to McCarthy, the new vehicle will be wider, more spacious and more suited to on-road driving – but won't lose its appeal as a true off-roader, and won't be aimed at a mainstream audience.

"It might attract some new buyers because of the changes to the interior," he said. "When you see the design its still G-Wagen, but it’s a pretty unusual niche, you either want a G-Wagen or you don’t. It's not going to be someone going ‘I was going to have a GLS 63 but ill have a G63,’ there is some potential for new sales, but there is only a handful of sales," he continued.

"It will be a better drive, but it hasn’t lost any off-road ability. I believe it has more. I believe on-road it will be a better vehicle."

The current G350 is priced at around $160,000 (plus on roads) with the G63 costing about $225,000. There isn't expected to be a huge change in price with the new model.

The V12-powered G65 will likely continue production, however it will still be unavailable for Australian market. Blame the big engine for that one – the steering column doesn't fit on the right-hand side of the car, ruling out right-hand drive.