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Guide · Used Tesla

Tesla Hardware 3 vs Hardware 4: what a used buyer should know

Two used Teslas from the same year can carry different self-driving computers. Here is what separates Hardware 3 (HW3) from Hardware 4 (HW4), which cars have which, how to tell, and how much it should matter to you.

Last updated October 8, 2026

The short version

Computer details come from published teardowns. Everything here is as of October 2026.
Hardware 3 (HW3)Hardware 4 (HW4, also called AI4)
Cameras1.2 megapixelsAbout 5 megapixels, with red-tinted lenses
Computer12 processor cores and 2 neural network accelerators20 processor cores and 3 accelerators, with faster memory
BuiltFrom about April 2019From 2023
Full Self-Driving softwareA lighter "Lite" version of the current releaseThe full current release, first
Driving with no one supervisingTesla says HW3 cannot do itTesla says HW4 is capable of it. What Tesla sells today is still supervised
Upgrade to HW4No program, price or date as of October 2026Not needed
Dashcam and Sentry videoLower resolutionSharper, and adds side pillar camera recording

Which cars have which

These are rules of thumb. Tesla changes parts in the middle of a model year, and cars built near a changeover can go either way, so always confirm on the car.

  • Model 3. 2019 to 2023 cars have HW3 (the very earliest, before about April 2019, have the older Hardware 2.5). The redesigned 2024 and later Model 3 has HW4.
  • Model Y. HW3 until 2023. HW4 began on cars built from late May 2023, so a 2023 Model Y can have either one.
  • Model S and Model X. HW4 from early 2023.
  • Cybertruck. HW4 from the start.

How to tell which one a car has

  • Ask the car. On the touchscreen, open Controls, then Software, then Additional Vehicle Information, and read the computer line. If your car does not show one, the cameras will tell you.
  • Look at the cameras. HW4 camera lenses have a red tint. The cameras in the front fenders also sit in a narrower housing.
  • Ask us. We check the screen on every Tesla we sell and put the answer on the listing.

What it means for Full Self-Driving

Full Self-Driving (FSD) is Tesla's driver assistance software. It steers, brakes and navigates, but the driver must supervise at all times. As of October 2026 Tesla sells it only as a subscription, at $99 a month. Buying it outright ended in February 2026.

Both computers run it, but not equally. New versions arrive on HW4 first. HW3 cars were held on an older version for more than a year, then received a lighter "Lite" edition of the current software in mid 2026. Some features need HW4.

The bigger difference is the future. On Tesla's April 2026 earnings call, Elon Musk said Hardware 3 does not have the capability for unsupervised driving, and described an upgrade as replacing both the computer and the cameras. On the July 2026 call he said upgrading older cars would make sense. As of October 2026 Tesla has announced no upgrade program, price or date.

If a previous owner bought FSD outright, Tesla says it stays with the car unless that owner moved it to another Tesla before the transfer program ended on March 31, 2026. A subscription does not carry over. FSD is not included with our cars unless the listing says so in plain words. The "FSD computer" line on a listing names the hardware in the car, not the software.

How much should it matter to you?

  • It matters a lot if you plan to subscribe to FSD and want the newest features first, or you are buying partly for where the software is headed.
  • It matters a little if you want the sharper dashcam and Sentry video.
  • It barely matters if you want a good electric car to drive yourself. Range, charging and comfort do not depend on which computer is installed.

Either way, the battery deserves more of your attention than the computer. See the Recurrent Range Score, explained.

See Teslas in stock → Used Model Y guide Used Model 3 guide

HW3 and HW4 questions

Can a Hardware 3 Tesla be upgraded to Hardware 4?

Not today. The HW4 computer is not a drop-in replacement: it has a different shape, different connectors and needs different cameras. Elon Musk has talked about upgrading older cars, most recently on Tesla's July 2026 earnings call, but as of October 2026 Tesla has not announced a program, a price or a date.

Does Hardware 3 still get Full Self-Driving updates?

Yes. In mid 2026 HW3 cars received a "Lite" edition of the current FSD software, and updates have continued since. HW4 cars get new versions first and get some features HW3 does not.

Does a 2023 Model Y have Hardware 3 or Hardware 4?

It can be either. Tesla began building the Model Y with HW4 in late May 2023, and HW3 cars were still being built for some months after that, so the build date alone does not settle it. Check the car's software screen, or ask us.

Is Full Self-Driving included with a used Tesla?

Only if a previous owner bought it outright and did not move it to another car, according to Tesla. Otherwise it is a $99 a month subscription from Tesla, as of October 2026, and it works on both HW3 and HW4 cars.

Does the computer affect range or charging?

Not in a way you would notice. The battery and the charging speed are the same either way. Teardowns found the HW4 computer draws somewhat more power, and a few newer camera and safety features need HW4.

Keep reading

Hardware 4 Model Y waitlist

Be first to hear when an original-body Model Y with HW4 arrives.

Used Tesla Model Y

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Used Tesla Model 3

Years, battery types, warranty and what is in stock.

Sources