SubQuery Question

I am trying to make a query and subquery work, but no luck with the query. 
 
In the sample query below, I want to get a count of the number of different car models that 
have been sold during a specified period of time. The subquery below works fine. Since I am
using this in a stored procedure, I want to select the count of values returned by the subquery 
below ainto a variable and work more with it. 
 
How do I put a count wrapper around the subquery enclosed in parenthesis below ?
 
select into <count-variable> count(*)  ..   where  ...
      (select distinct auto_model from car_lot 
      where date_sold between '2005-01-01 00:00:00' and '2005-01-31 23:59:59') ;
 
It seems like I should be able to do this is with one SQL statement. 
 
I considered inserting the sub-query answer into a temp table, then counting the records in the 
temp table, but don't want to incur the I/O. If I could stuff it into an array, then count the array, that 
would work also, but not sure how to do that. 
 
Does anyone have any thoughts?