THEORY: I HAVE $10,000 IN MY BANK ACCOUNT. IT EARNS $1 PER DAY IN
INTEREST.ON MAR 1ST I BUY A CAR FROM ABC MOTORS FOR $10,000 AND PAY BY
CHEQUE.ON MAR 2ND MY SAVINGS IS ZERO. ABC MOTORS IS NOT CREDITED FOR
MY $10,000 UNTIL MAR 10TH (CHEQUE CLEARANCE POLICY-TWO BANKS
INVOLVED). THE BANKS EARN THE INTEREST ON MY MONEY FROM MAR. 2ND UNTIL
MAR 9TH.HOW DO BANKS SHOW THIS ACCUMULATED REVENUE STREAM ON THEIR
ANNUAL STATEMENTS? ANY INDICATION OF WHAT THIS AMOUNTED TO FOR RBC IN
CANADA IN THEIR LAST FISCAL YEAR?

A question back: On what date will your bank debit your account? 
Presumably not the date you wrote the check but the day it was
presented.  With electronic clearing, that could be March 3 or 4.

But anyway, there can (is) a difference between the date you are
debited and the date the auto co is credited, called "float".  The
funds are available to the bank or banks (not both at once) for a day
or two as funds on their clearing accounts, probably with the central
bank.  The interest the bank earns just goes into its books as
interest income, maybe in Canada this is broken down in some way, but
I doubt it, and certainly not in a way that one could identify the
interest earned from the float.

I appreciate your answer. My bank debits my account on Mar 2nd - I've
transacted the deal electronically. So, this "float " interest is "
swimming "  out there for [say ]4 days. Which bank gets the interest?
Both ? What about the central bank ? The revenue generated by banks in
"float" interest must be in the hundreds of millions annually.

If you made an electronic transfer, then cheque-clearance policy would
not apply, so ABC Motors would get the money a lot sooner.  There are
policies on this now too, however.  I searched with "electronic
transfers" "clearing rules" and found 39 hits.  Here is one for the UK
as I didn't find anything from Canada:

[PDF] Blue Book United Kingdom 2001
Dateiformat: PDF/Adobe Acrobat - HTML-Version
... electronic transfers in both debit and credit form. The clearing is operated
by BACS Ltd.The BACS ... relevant clearing rules. There are, however, no ...
www.bportugal.pt/euro/emudocs/ bce/b_book/2001/BlueBook01UK.pdf - 

and here is another from the States, where checks are still the
primary means of payment and are now cleared electronically:

http://www.vscpa.com/Advocacy/check_21.htm

Here is a Canadian court case that   float "clearing rules" canada 
found, but I have not read it:
http://reports.fja.gc.ca/fc/1999/ori/1999fc25255.html

I won't say that it could not occur that the bank of ABC Motors might
find an excuse to value date the credit of the $ 10,000 one or two
days later.  The receiver of funds is usually just happy to get them
and may overlook the delay, indeed, may not be able to recognize it,
since he probably won't know which date the transfer was made.
The central bank doesn't get anything, since the funds are only in the
one or the other bank's account.  I expect (just my guess!) that they
each get a day or two's float.
How much do banks earn on float?  
Maybe a researcher could find someone's estimate of average days'
float on transactions in one country and a statistic on the volume of
transactions and calculate on from the average interest rate what the
banks earn.  One problem in this would be that the really big money
that makes up most of the transaction volume (billions in foreign
exchange and money market transactions) get same day credit  - no
float.
(As usual, the little guy gets shafted.)
Interesting question.  Don't think I can add anything more.
Regards