About this detail of the Tiger
In February 1944, a device was added to the Tiger for cold-starting the engine. It allowed the crew to heat the engine via its cooling water supply, from outside the tank.
This device was added at the same time as the new "steel wheels", which are provided in Hachette's kit. Therefore the kit should have the access port for the heating device, indicated in this photo.
The port is missing from the Hachette Tiger Tank, according to these photos. You could improve accuracy by adding it.