using System.Linq.Expressions;
using MongoDB.Driver;
using MongoDB.Driver.Linq;
var mongoUrl = MongoUrl.Create("mongodb://admin:123456@localhost/management_reports?authMechanism=SCRAM-SHA-1;authSource=admin;minPoolSize=1;retryWrites=true");
var clientSettings = MongoClientSettings.FromUrl(mongoUrl);
clientSettings.LinqProvider = LinqProvider.V3;
var client = new MongoClient(clientSettings);
var db = client.GetDatabase("test");
var carCollection = db.GetCollection<Car>("cars");
var updateDef = GetUpdateFieldDefinition((t => t.Type, "super-fast"), (t => t.Price, 100m));
await carCollection.UpdateManyAsync(t => t.Type == "fast", updateDef);
Console.ReadKey();
static UpdateDefinition<Car> GetUpdateFieldDefinition(params (Expression<Func<Car, object>> fieldSelector, object value)[] fieldsToUpdate)
{
    UpdateDefinition<Car> updateDefinition = null;
    foreach (var (fieldSelector, value) in fieldsToUpdate)
    {
        updateDefinition = updateDefinition?.Set(fieldSelector, value) ?? Builders<Car>.Update.Set(fieldSelector, value);
    }
    return updateDefinition;
}
public class Car
{
    public string Type { get; set; }
    public decimal Price { get; set; }
}