code show as below:

# -*- coding:gb2312 -*-

# 定义类
class Car:
    # 移动
    def move(self):
        print('车在奔跑...')

    # 鸣笛
    def toot(self):
        print("车在鸣笛...嘟嘟..")
        
    def introduce(self):
        print("车的颜色是%s，轮子数量是%d"%(BMW.color,BMW.wheelNum))


# 创建一个对象，并用变量BMW来保存它的引用
BMW = Car()
BMW.color = '黑色'
BMW.wheelNum = 4 #轮子数量
BMW.move()
BMW.toot()

BMW.introduce()

print(BMW.color)
print(BMW.wheelNum)

Results of the:

My question, this error message:
What does inconsistent use of tabs and spaces in indentation mean?
I used Google to translate it, it means:
Inconsistent use of tags and spaces in indentation

The problem is that I checked and can't see any errors.

As shown in the picture, I blocked the wrong line with comments, and the program can run automatically. In other words, other indented lines juxtaposed with the wrong line can run smoothly. So I can't see what's wrong.

# -*- coding:gb2312 -*-

# 定义类
class Car:
    # 移动
    def move(self):
        print('车在奔跑...')

    # 鸣笛
    def toot(self):
        print("车在鸣笛...嘟嘟..")
        
    #def introduce(self):  把错误的地方暂时屏蔽
        #print("车的颜色是%s，轮子数量是%d"%(BMW.color,BMW.wheelNum)) 把错误的地方暂时屏蔽


# 创建一个对象，并用变量BMW来保存它的引用
BMW = Car()
BMW.color = '黑色'
BMW.wheelNum = 4 #轮子数量
BMW.move()
BMW.toot()

#BMW.introduce()  把错误的地方暂时屏蔽

print(BMW.color)
print(BMW.wheelNum)

Results of the:

As shown in the picture, I blocked the wrong line with comments, and the program can run automatically. In other words, other indented lines juxtaposed with the wrong line can run smoothly. So I can't see what's wrong.