PUT Vehicle - PHP

<?php
   $token = 'TOKEN_STRING';
   $FIM_app_id = 'APP_ID';
   $FIM_endpoint = 'https://fim.api.ENV.fleetmatics.com/cmd/v1/vehicles/';

   //Set local variables
   $vehicle_number = 'VEHICLE_NUMBER';
   $vehicle_reg_number = '12345HAQS';
   $vehicle_vin = '12FG4561523A415F153';
   $vehicle_make = 'FORD';
   $vehicle_year = '2012';
   $vehicle_model = 'Fiesta';
   $vehicle_tankCapacity = 20.5;
   $vehicle_highwayMPG = 14.5;
   $vehicle_cityMPG = 11.5;
   $vehicle_size = 1;
   
   //Using variables, create an array to store data for PUT. Note: '=>' is necessary
   $put_data = array('RegistrationNumber' => $vehicle_reg_number,
                     'VIN' => $vehicle_vin,
                     'Make' => $vehicle_make,
                     'Year' => $vehicle_year,
                     'Model' => $vehicle_model,
                     'TankCapacity' => $vehicle_tankCapacity,
                     'HighwayMPG' => $vehicle_highwayMPG,
                     'CityMPG' => $vehicle_cityMPG,
                     'VehicleSize' => $vehicle_size					 
                     );

   //Call method
   echo put_vehicle_info($vehicle_number, $put_data, $FIM_endpoint, $FIM_app_id, $token);

   function put_vehicle_info($vehicle_number, $data, $endpoint, $app_id, $token)
   {
       //Append vehicle number onto the end of the endpoint string for a complete url
       $url = $endpoint.$vehicle_number;  
   
       //Get necessary headers for REST call
       $headers = get_call_headers($app_id, $token);
       
       //convert data to JSON format
       $json_data = json_encode($data);
       
       $session = curl_init($url);                                 //Initialize transfer with URL
       curl_setopt($session, CURLOPT_CUSTOMREQUEST, "PUT");        //Set to PUT transfer request type
       curl_setopt($session, CURLOPT_RETURNTRANSFER, true);        //Return transfer as a string of the return value of curl_exec() 
       curl_setopt($session, CURLOPT_HTTPHEADER, $headers);        //Pass in headers 
       curl_setopt($session, CURLOPT_POSTFIELDS, $json_data);      //Pass in PUT data 
   
       //Execute transfer of $session    
       $response = curl_exec($session); 
       
       //Get http code outcome of the #session transfer    
       $http_code = curl_getinfo($session, CURLINFO_HTTP_CODE);
       
       //Measure false response/error
       if($response === false)
       {
           echo 'Error: '. curl_error($session);
       }
   
       //ALWAYS close transfer connection 
       curl_close($session);
        
       //Evaluate variable for non 204(No Content) http code
       if($http_code !== 204)
       {
           echo 'Error: Http Status Code returned '.$http_code;
       }

       return $response;    
   }
   
   function get_call_headers($app_id, $token)
   {
       //Inserts app_id and token into respective '%s' spaces in the auth header   
       $auth_header = sprintf('Authorization: Atmosphere atmosphere_app_id=%s, Bearer %s', $app_id, $token);
      
       //Create necessary headers for REST call   
       $headers = array();
       $headers[] = $auth_header;  
       //IMPORTANT! - You must use 'Content-Type' as opposed to Accept as you are describing how the info is being sent
       $headers[] = 'Content-Type: application/json'; 
       
       return $headers;
   }
?>