That estimate is incorrect and they delivered well over 100 cars total.
They are building 5 a week.
When is a car sold?
Sales reports are important. They can move markets. The numbers are reflected in corporate accounting.
Are sales numbers "incorrect?" Or do they simply reflect a generally accepted method of accounting?
I believe (subject to being wrong) that the monthly auto sales data captures sales to final customers. But what is a sale? A sale is a transfer of title.
A car is made in November, put on a transporter in December, paid for by a customer and delivered to the customer on December 31, with temporary title transferred to the customer on January 2. The car is reported as a sale in January (I think).
So, if I have that right, the sales reports are "correct," but still subject to revision for errors. However, sales reports will never match production reports. Sales reports should be close to delivery numbers though, especially for the GT where I expect very little lag between transport and title transfer to the customer. GTs are not going to sit in dealer inventory.
If you accept sales reports as real numbers (not estimates), then the discrepancy between sales (~80?) and "delivered well over 100" is hard to explain if delivered = sale (i.e., in the hands of the customer).
Of more interest to most of us than this accounting exercise is "they are building 5 a week." This represents the full planned production rate and is, I think, full production capacity. Which means there cannot be a catch up to the planned 1,000 cars in four years.
Assuming 100 GTs produced in year one, the simple math says that production is lagging the plan by 30 weeks (150 cars behind plan divided by five cars per week equals 30 weeks).
This leaves three scenarios:
1. Production can somehow be increased to six cars per week (which would allow about 1,000 cars in four years of production if it took effect immediately).
2. Production will be extended beyond four years to reach 1,000 cars.
3. Production will cease after four years with fewer than 1,000 cars (~850?).
Scenario 3 would be the sad trombone scenario.