Customers who have already reserved their Tesla Model X electric sport utility vehicle are now able to choose paint color, wheel size and a “ludicrously fast” speed option, according to Bloomberg.

The start of personalization options is a good indicator that production of the vehicles is on schedule. The company has said that deliveries will begin at the end of September.

Reservation holders can now choose their Model X Signature vehicle in either Signature Red, Titanium or Deep Blue.

The “Ludicrous Speed Upgrade” comes as an add-on for an extra $10,000.

The limited edition in the Signature series is available for $132,000 and has already been reserved by hundreds of people.