Are you in serious off road conditions 80-90-100% of the time?
I am currently rolling two more cruisers - a 150 Prado and an 80-series.
Frequently swap them between my group of friends, owning mostly defenders and patrols.
I will discuss fuel economy first. There is no scientifically sound experiment to prove that there is, indeed, an increased overall economy.
As physics teaches us, it's the driving style, vehicle weight, and vehicle aerodynamics that account for the majority of the fuel figures. Driveline losses are negligible if the car is well maintained.
On the contrary, my experiments prove the opposite:
- Running my part-time Troopy with and without hubs locked yielded no visible fuel economy on a 500km round-trip that I do weekly while my son is on vacation at his grandparents. 50% highway, 50% mountain county roads. Checked multiple times.
- I have double the tire wear on the rear than on my other full-time 4wds, which means more frequent tire rotations and tires that will last less km.
- RWD is very unstable on slippery road conditions; everyone can confirm this.
- There is increased wear on the front and rear axle on part-time 4wd vehicles that have been wheeled offroad than on full-time 4wd. Maybe because wheeling in a permanent 4wd rarely you need to lock the center, and you usually unlock it immediately once you get unstuck. Wear is the same on full-time vehicles on which the driver permanently engages the center lock while in 4Low, though. Those guys are mostly part-time drivers who now drive or own full time and are not used to how it drives.
- Tight corners on rocky forest roads, especially off-camber, are really scary with a locked center (which all part-times are, basically).
- On part-time, there were a lot of occasions that I've witnessed when front hubs were found to be stuck just before hitting the trail. Never happened on a full-time.
As you can see, there are not too many advantages of a part-time 4wd. Part-time is a relic of the past when trucks were designed as RWD and 4WD retrofitted.
A full-time transmission solves all the increased wear disadvantages that a part-time 4WD has. Frequent rebuilds on full-time front axles are a myth.
And the best thing, it handles light years better on and offroad than any part-time, which translates into increased safety and reliability.
Especially on-road, you get neutral steering response, which is a very reassuring and relaxed driving experience, no matter the driving conditions.
As a driver of both, I cannot see what part-time offers that full-time does not deliver better.