Instrument cluster upgrading?

Here is the information I found on the job you want to do:

It is possible to upgrade the instrument cluster in your 2012 Dzire LDI model to the one found in the VDI or ZDI models that include an RPM gauge, as long as the wiring and couplers match.

Please let us know if you need anything else to get the problem fixed.

The primary issue with this type of upgrade isn't in the wiring as the makers tend to use a harness that covers all options for the model even if it doesn't have that item. However, that option may need to be activated in the powertrain or body module for it to actually work. For instance, your vehicle may have all of the wiring in place for fog lamps but not have the actual lamps, relay and interior switch. So, you go buy those parts and install them only to find that you need a scan tool and a dealer option code to be able to make them work. In this case it may need the option code for the up-level vehicle for the cluster to operate. Unfortunately, most manufacturers don't release that type of information and instead it is discovered by enthusiasts or owners when they decide to just plug things in and see what happens. In your case you may want to search and see if there is an owners' group or club
that perhaps has already tried this and has the info on how it was done. However, because of changes the companies make over the years don't assume that someone saying that they did this in a 2008 and it worked fine will also apply to the 2012. They like to add and remove things from the options at a whim.