漏了2个别名：
select a.fn,fc1,fc2
from (select che_cx fn,count(*) fc1
from work_pz_sj group by che_cx) a
join (select chex_mc fn,count(*) fc2
from sm_peijcx group by chex_mc) b on a.fn=b.fn

------解决方案--------------------

SQL code
----------------------------
-- Author  :fredrickhu(小F，向高手学习)
-- Date    :2012-06-12 09:30:52
-- Version:
--      Microsoft SQL Server 2008 R2 (RTM) - 10.50.1617.0 (Intel X86) 
--    Apr 22 2011 11:57:00 
--    Copyright (c) Microsoft Corporation
--    Enterprise Edition on Windows NT 6.1 <X64> (Build 7600: ) (WOW64)
--
----------------------------
--> 测试数据：[work_pz_sj]
if object_id('[work_pz_sj]') is not null drop table [work_pz_sj]
go 
create table [work_pz_sj]([id] int,[che_cx] varchar(4))
insert [work_pz_sj]
select 1,'奥迪' union all
select 2,'奥迪' union all
select 3,'宝马' union all
select 4,'奔驰'
--> 测试数据：[sm_peijcx]
if object_id('[sm_peijcx]') is not null drop table [sm_peijcx]
go 
create table [sm_peijcx]([id] int,[chex_mc] varchar(4))
insert [sm_peijcx]
select 1,'奔驰' union all
select 2,'奥迪' union all
select 3,'宝马'
--------------开始查询--------------------------
select
  a.che_cx as 车型,count(a.che_cx) as 数量
from 
  work_pz_sj a join sm_peijcx b
on
  a.che_cx=b.chex_mc
group by
   a.che_cx

----------------结果----------------------------
/* 车型   数量
---- -----------
奥迪   2
宝马   1
奔驰   1

(3 行受影响)
*/