Hi Avril,
I'm a confirmed Mercedes nut - and the Cherokee 3.1 engine from the Italian VM company predates the excellent Mercedes 2.7 and 3 litre CDI engines fitted to Cherokees just a couple of years later...
In terms of power and torque, the 3.1 is way down on output compared to even the oldest Mercedes 2.7 diesel unit - the power difference is roughly equivalent to that from a small car...
Low powered engine in a big heavy body equals bad fuel consumption...
And VM didn't have the best reputation for quiet engines...
Robert