How different are HW3 and HW4 in everyday driving?
Running the same route on each platform with self-driving engaged and comparing them side by side, the video's core finding is that everyday driving shows almost no difference between the two generations. Across a full city-and-highway round trip the driver never touched the wheel or pedals, and both cars drove smoothly.
The interesting part is that HW3 is already old. Stuck on the same FSD build (v12.6.4) since early 2025, it still handled highway merges, lane changes, and city driving reliably. Tesla has quietly layered small refinements onto that same build, and its timing for slotting into merge gaps is said to have become more natural than before.
What HW3 still does well
HW3 even has a few things more convenient than the newer platform. The right scroll wheel lets you fine-tune the max speed in real time, so it is easy to dial the speed down or up to fit the moment. HW4 has no such fine-tune control.
But the limits are clear too. On city streets HW3 cannot switch the speed profile (chill, standard, hurry), whereas HW4 lets you change among five profiles even in the city. For reference, top FSD speed was capped at 85 mph regardless of hardware.
Where HW4 and v14 genuinely pull ahead
HW4's real advantage is in raw hardware. Inference is 3 to 5 times faster, it uses full-resolution camera input, and v14.3 rewrote the compiler and runtime on MLIR (multi-level intermediate representation) for 20% quicker reactions. None of these lower-level gains exist on v12.
The behavior differs too. HW4 and v14 can start self-driving straight from Park (HW3 requires shifting to a drive gear first), there is less hesitation at stops and less phantom braking, and lane changes feel more natural. In edge cases like handling emergency vehicles or complex parking, it is described as clearly better.
So what's the conclusion?
In short, HW3 is still plenty for the vast majority of owners. Everyday driving is fine on the older hardware, and HW4's real gap only emerges once you drive it long enough to repeatedly hit the tricky situations.
There is an implication here: top performance does not necessarily come only from the latest hardware. Software and model optimization can meaningfully extend the life of older hardware, and the real gap usually opens only in rare edge cases.