How to use method in separate groovy script within test case

For example, the following file is present at directory ../ReadyAPI-1.4.1/bin/scripts and we see how can this be accessed in two groovy script test steps in a project

Vehicle.groovy

class Vehicle {
   def name
   def yearMade
   def printModelDetails(log) {
      log.info "Vehicle is ${name}, made in ${yearMade}"
   }
}

Model.groovy -- assume this is your groovy script test step

import Vehicle

def vehicle = new Vehicle(name:'Merk', yearMade:1975)
vehicle.printModelDetails(log)
//saving value of vehicle name at test case level property say VEHICLE_NAME
context.testCase.setPropertyValue('VEHICLE_NAME', vehicle.name)

View.groovy

import Vehicle
//get the previously store value from test case property

def vehicleName = context.testCase.getPropertyValue('VEHICLE_NAME')
def vehicle2 = new Vehicle(name:vehicleName)
log.info vehicle2.name

Note that all the common stuff to be present in the first groovy class that is placed in scripts directory.

For more details see documentation