Tesla Motors only reveals its production figures every quarter, but it has now likely built up to 90,000 of its all-electric Model S luxury sport sedan.

The company also doesn't group its changes and updates into model years, but makes running changes in the cars whenever the updates are tested, validated, and ready to roll.

So how is a Tesla Model S built in October 2015 different from the first one sold to a paying customer (actually a Tesla board member) in June 2012?

DON'T MISS: 2014 Tesla Model S - Full Review

The shape is still the same, and there are still two battery-size options, though they have risen from 60 and 85 kilowatt-hours to 70 and 90 kWh.

New performance options have been added at the high end: A "Ludicrous" performance mode has joined the "Insane" mode pioneered on the P85D.

All-wheel drive "D" versions are now available, based on the dual-motor system developed for the Model X crossover utility vehicle first delivered last month.

2014 Tesla Model S in China

But under the surface, there are a surprising number of updates, additions, and new features, many of them additional-cost options.

Our thanks to Tesla communications staff Alexis Georgeson and Shanna Hendriks, who patiently compiled a list of all the hardware and options changes made to the cars since the start of 2013.

[EDITOR'S NOTE: This article was first published in June 2014; we have now updated it to reflect additional Model S updates from that date through October 2015. The new material is throughout the article.]

This list doesn't cover Tesla Model S software changes, of which there are literally dozens, grouped into minor and major releases that are pushed over the air to the car once the owner gives permission for the update to occur.

Tesla owners will undoubtedly flag any hardware features we've left out, described incorrectly, or otherwise gotten wrong in the following list--but here's what Tesla Motors sent us.

July 2015

New 90-kWh battery introduced in 90 (RWD), 90D (AWD), and P90D (performance AWD) versions

Ludicrous performance mode added for 0-to-60-mph acceleration in 2.8 seconds

Rear-wheel-drive 70 version added, starting at $70,000

April 2015

New 70-kWh battery introduced in 70D version, replaces 60-kWh battery

October 2014

Dual-motor (or "D") all-wheel drive option offered on 85-kWh versions: 85D and P85D

September 2014

All Model S cars now built with standard Autopilot sensor and control hardware

January - April 2014

Titanium three-piece battery safety shield (standard equipment from March 2014; can be retrofitted to any Model S)

Addition of Park Assist option (can be retrofitted to vehicles built after August 1, 2013)

Power Sunshade for inside of rear liftgate

2014 Tesla Model S

MORE: Life With Tesla Model S: Battery Upgrade From 60 kWh To 85 kWh

January - December 2013

Power folding mirrors (now included in Tech Package; can be retrofitted to vehicles built after August 1, 2013)

Red brake calipers (now included in Performance Package)

New wheel option: 19-inch Cyclone / Turbine Wheel (joins previous 21-inch Cyclone / Turbine and 19-inch Aero wheel options)

Cold-Weather Package (cannot be retrofitted)

Fog Lamps (improved design illuminates a low, broad area below the low-beam's light path; can be retrofitted to any Model S)

Parking Sensors (can be retrofitted to any Model S)

Ultra-High-Fidelity Sound Package (cannot be retrofitted

ALSO SEE: Life With Tesla Model S: One Year And 15,000 Miles Later

Three-Zone, Three-Mode Rear Seat Heaters

Wiper-Blade Defroster

Washer-Nozzle Heaters

Performance Plus Package (upgraded dampers, bushings, stabilizer bars; rear tires 20 mm wider and staggered for better acceleration on low-grip surfaces)

Premium Leather Trim (adds leather on the top pad and lower area of the instrument panel, the door panel, the lower pillars, the armrest, and the driver-side airbag cover)

Premium Interior Lighting (ambient lighting elements in passenger cabin and rear load bay)

Mobile App availability

"It should be noted," Hendriks wrote, that none of these are mandatory changes--they are merely options that have been added to the roster" of available equipment when ordering a new 2014 Tesla Model S.

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