post 2003 1HDFTE Cruisers are completely different package when compared to the 98-02 ones.
This one came with a VN Turbo which means effortless low end acceleration and a good fuel economy too. The pre 2003 came with a fixed geometry turbo CT26 (i guess) but this one had a Garrett GT2359V with vane control through a electric VSV.
Coming to transmission, the a750f simply beats the older a442f both in economy and acceleration but because they are more refined than the 4spd ones, sometimes they can become a pita if not serviced properly. you will need a complete fluid exchange anyways ( around 10 litres will be used )
The engine itself behaves quite differently when compared to the pre 2003 ones (thats what i felt). Its a bit free-reving and little bit clacky compared to the older models.Other than that the 5spd models adopted a water-cooled type EGR system (older ones were air cooled) and a throttle to aid the egr flow.
Check the service history and do ask questions about the work that has been done by the existing owner. If he sticks to the usual rant of "siraf haail chenge karaya aj tak" then be ready for injector service and valve clearance, also the air path needs to be throughly cleaned as it would be caked up probably due to egr soot build-up.
Other than that the VN Turbocharger itself is a pita when needs to be replaced. (a brand new one costs around 1500 USD from Toyota) These turbos usually go bad around 150,000 kms on these LC's (usually starts to leak from the centre shaft) so have it examined properly before you buy it.
The AHC system on these is another nightmare for both the owner and the ustaadjee. Usually one of the sensors goes bad but mudaa ustaad actually believes in "pura kabulee unit paa deyo" so you'll end up in tears after looking at the repair bill.
Now coming to the fuel consumption.
The entire fuel economy figures are based on my personal experience of driving all the 3 LC100's i have rn.
2000, 2005, 2007
Both(5spd) the 2005 and 2007 return me with mileage of 8 - 9 kmpl within city and 11 - 11.5 kmpl on highways (if kept at 120) below 120 lets say 100 km/h gave me around 13kmpl. But life's too short to drive slow in the middle lane.
The 2000 (4spd) one gives me around 6 -7.5 kmpl in city and around 9 on highways at 120. At 100 gives me around 10kmpl.
Anyways its a good SUV actually a blessing specially when you're a diesel lover. But for that first you need to get it back to factory specs which means no jugaarbazi.