import json

def model_by_plate(js, plate):
    for car in json.loads(js)['cars']:
        if car['plate'] == plate:
            return car['model']

print(model_by_plate(data, 'E222EE177'))

import csv
import xml.etree.ElementTree as ET


xml_data = """<?xml version="1.0"?>
<Root>
    ...
</Root>"""

root = ET.fromstring(xml_data)

header = set()
rows = []

for subroot in root:
    row = {}
    for level in subroot:
        header.add(level.tag)
        row[level.tag] = level.text
    rows.append(row)

with open('out.csv', 'w') as file:
    writer = csv.DictWriter(file, fieldnames=sorted(header))
    writer.writeheader()
    writer.writerows(rows)