我认为你可以使用 insert 和 map by Series 使用 df2 创建(如果 MODEL 列中的某个值df2 中的 缺少 get NaN):

I think you can use insert with map by Series created with df2 (if some value in column MODEL in df2 is missing get NaN):

df1.insert(2, 'MAKE', df1['MODEL'].map(df2.set_index('MODEL')['MAKE']))
print (df1)
   ID    MODEL        MAKE  REQUESTS  ORDERS
0   1     Golf  Volkswagen       123       4
1   2   Passat         NaN        34       5
2   3  Model 3       Tesla       500       8
3   4       M3         BMW         5       0