Here in Norway, LWB Gs have been available as 2-seater, 5-seater, 9-seater and 10-seater versions, with 2, 5 and 10 being available from the factory.
The 10-seater is a peculiar Norwegian adaption that was made for tax reasons, since it then could be registered as a minibus with a much lower purchase tax (20% of the tax for the 5-seater). This tax makes up around 50% of the purchase price of a new G around here.
The 10 seater has the usual 5 seats, plus a rear-facing folding seat mounted on the backrest on the rear seat as well as two-seater side-facing folding seats on each side of the rar compartment.
The rub of the minibus registration is that you need a minibus drivers license, so the license will cost you extra.
The 9-seater version became another variant. If you want to de-register a minibus and reregister it as a normal car, you have to pay the remaining 80% of the tax. The amount you have to pay will go down as the car ages, so that after 10 years, you dont have to pay more than $200 to re-register it as a normal car. However, if you want to re-register it, you can't have more seats than it's registered for, so therefore it's common to rip out the rear-facing seat and then register it as a 9-seater normal car (the max number of seats before you need a minibus registration).
My car once was a minibus with 10 seats, however, the PO ripped out all the seats in the rear compartment and registered it as a 5-seater.
Nowadays, you can't register a new G as a minibus, since sidefacing seats are no longer allowed. The only way to lessen the purchase tax on a G now, is to register it as a 2-seater van or truck. Then you only have the 20% tax. (Before a truck registration had no purchase tax, but needed a truck drivers license. Now, the tax is the same, so no truck registration Gs are available.)
The 270CDI used to be NOK570 000 ($86500) as a truck and NOK970 000 ($147000) as a 5-seater. The G400, G500 and G55AMG are correspondingly more expensive. The purchase tax consists of 3 parts - weight tax, displacement tax and engine power tax. The G (and all other large SUVs) are heavily taxed on all three areas. In addition, you get a 25% sales tax on top of it all.
Regards
Johan-Kr