It's all about engine specs luna.
The VX 3.5L is a low compresion engine,that's why it use 87 regular octane gas & produce 215 hp which if fact was a lot of power back in the late 90's according to my mech the VX was one of the most powerfull V6 SUV world wide,just after the nissan pathfinder which had 240 hp ( all 2001 edition ) even more then few V8 SUV's out there back in those days.
The nissan Z350 which is a high performace car with a high compresion ratio that requires higher octane gas,plus both vehicules have different gross weight,ground clearance,etc.
Don't forget that the VX engine is a 13 years old engine,if the latest version of isuzu 3.5L that you find in the 2004 axiom can the use in the VX you'll definately have more power.
The 2004 isuzu 3.5L engine kicks 250 HP with direct injection technology. Unfortunately isn't compatible with the VX
Dakar was just the begining.