trip computer Inverting resistance

Hi i was wondering if it was possible to invert the resistance with electronic components?

Firstly i beleive im right in the fact that modern fords use resistance as the signal input for fuel gauges and not current or voltage!

i have fitted a ftrip computer to a car that never had one fitted i have got everything working fine except for the fuel range to empty

my car has 20 ohms resistance at a Full Tank of gas and 150 ohms empty , but the imput required is 220ohms Full and 50 ohms empty  if anybody knows if this can be acheived using electronic components or if there is another way to do this (without changeing sender unit) any help would be appreciated . The Trip computer is from a 1995 UK spec Ford mondeo

negative resistance can be done and is kinda cool to see, it can be done with tunnel diodes and opamp circuits... but i dont think those ideas would really work...

One thing, although it varies resistance it is using it to drop a voltage on and then measure the voltage...

how much is the new sending unit?

Im trying to think of a way to do it cheap.... what about pulling the sending unit and wiring to the other side of the resistive element the arm sweeps against? not too sure if thats possible...

hah my first car never had a working gas gauge and I would have to watch the odometer to know when to get gas.. now thats annoying!