with respect, I think that statement is flawed by some manufacturers.
I have personally been thru the Honda plants in Ohio. They cast and machine the engines and parts, stamp body parts, paint, assemble, ship, all from right there.
So explain to me how lots and lots of money goes back to Japan.
Please be specific.
When it comes to the "cost of manufacture" of a piece of inventory (in this case an automobile) it has nothing to do with the "dealer cost" or invoice. Typically the dealer invoice is more than double what it actually costs in parts, labor and production facility expenses to produce that vehicle.
To keep the numbers easier to deal with, I will use 40% as an example (many vehicles' production costs are far less than this number).
It is generally agreed amoung US economists (both liberal and conservative) that money spent in the economy has an effect far greater than the actual dollar amount. What happens is the money gets re-spent a number of times till it is worn away by consumers' marginal propensity to save (they won't spend every cent they receive, they will save some). Money spent in the consumer market (as opposed to government spending) is normallyy respent 9 times (for this type of purchase the miltiplier effect is 9).
Take the Toyota that is built in Mudbank Mississippi. It is shipped to a dealer, and that dealer pays Toyota 20,000 bucks for it, the sticker has a MSRP of 23,500. The economy really stinks, so the dealer sells it at "cost" which is what he paid (20,000 bucks).
$12,000 of the money you gave the dealer is sent to Japan, it is forever removed from the US economy. The other $8,000 goes to Mudbank Miss, and gets distributed to the various employees, suppliers and contractors that supplied goods and services necessary to build that car (assuming all the parts were sourced in the US - not very likely)
So, your 20,000 dollars you initially spent had a potential economic stimulus of $180,000 to the US economy ended up only providing, at most, $72,000 worth of stimulus.
The situation reverses somewhat when a US manufacturer outsources his manufacturing. The example of the Ford made in Canada (or Mexico, or any other country). If production costs are significantly less for Ford to offshore their car production, their corporate profit is greater per unit than if that product were made in Detroit. This offsets to a degree the stimulus lost by paying foreign workers to build the cars. If sub-assemblies are US made, then the loss is less.
The Car company still earns their profit, but there is a big difference where that profit goes, and whose economy benifits from that profit.
Yes, this is a gross oversimplification, but the basic mechanics of the process is correct.
edit to add: sorry about using the "stimulus" word, it seems popular these days. "economic activity" can be substituted if you wish.