Actually yes, they are noticeably more efficient than other electric vehicles in their class (similar weight and range). One example shows Tesla as 20% more efficient:
Comparing Model 3 vs Bolt on efficiency is just aerodynamics. A lower, longer car is of course more efficient than a taller, shorter one.
The Hyundai Ioniq is a similarly shaped EV as the Model 3, and it gets very similar numbers - 133 MPGe (Ioniq) versus 141 MPGe for the best version of the Model 3 Standard Range, a difference that's smaller than going from 18 to 20 inch rims on the Model 3 Long Range Performance.
It is essentially useless to compare cars that are within 10 MPGe of each other at 130+ MPGe. If your tires are slightly off optimal pressure, or you've left something heavy in the trunk, or you've chosen different rims than standard, you've lost more than this. God forbid if you've put on a roof rack, probably drops you 30 MPGe down to 100-ish.
This discussion also underpins why MPG is a poor unit to measure efficiency with. The inverse measures used in Europe like L/100km or kWh/km are much easier to compare, as differences can be compared directly between a low and a high efficiency car
I agree that subtraction is not especially helpful when comparing two cars fuel efficiency using MPG. A simple way to frame it is that doubling MPG halves your fuel needs for the same distance.
It's tough to find fair comparisons. The Ioniq for example weighs 500 lbs less than the Tesla and has significantly less range as well.
In addition to aerodynamic improvements (which is of course a non-trivial engineering effort), Tesla does have a unique rear motor design that is more efficient, an industry-leading inverter design, and many incremental engineering efforts that cumulatively save several percentage points. Because they are "all-in" on an EV design they don't have to compromise because of a shared EV/Hybrid vehicle frame design for example.
The EPA listings also provide kWh/100 miles which I use for comparison to avoid the unfair MPGe equivalency.
Yeah, I'm not saying the Tesla is poorly engineered. But OTOH it seems hard to argue they have some special sauce that gives them 20% advantage over everyone else. I don't see how they have a moat - partly because designs are already running close up against the fundamental physical limits e.g. in aerodynamics and power electronics.
Another example: the Hyundai Kona is a purely electric platform that doesn't need to compromise, and it matches the efficency of the Model Y.
The Hyundai Ioniq is a similarly shaped EV as the Model 3, and it gets very similar numbers - 133 MPGe (Ioniq) versus 141 MPGe for the best version of the Model 3 Standard Range
The Ioniq has substantially less range than the Model 3, and is a much smaller car. If the Model 3 still gets slightly better MPGe despite those differences, I'd say Tesla still has a pretty significant efficiency advantage in this comparison.
According to the specs on interior dimensions listed on fueleconomy.gov, the Ioniq is actually bigger - 96 cu ft passenger and 23 cu ft luggage volume, vs. 97 cu ft passenger and 15 cu ft luggage for the Model 3.
So they've sacrifised range by installing less batteries, gaining more luggage space, lower weight and lower price.
They have some advantage in technology, but so far they are just ahead, but usually not by leaps and bounds. They have the most experience with the drive train, the battery and the self driving. However the real 'moat' they have, is producing EV profitably, as far as we know, the other auto makers, at least until this year, were never making money of EVs. At least Ford/GM will probably continue like that, the new Electic Mustang on paper competes with Tesla but uses a battery twice the size, meaning that it can not be very profitable, if at all.
Tesla last Qt showed 25% margin on their cars. That is higher then most OEM get on their cars (usually its cheaper cars to be fair). Other OEM don't report the margins on their EVs, but most analysis shows that they make basically no money, and very often negative money.
Tesla is pushing on batteries like crazy and trying to vertically integrated and innovate both on the chemistry and on the packaging. Most OEM buy battery cells from the same 3 companies, and that often leads to delays for all of them. LGChem in Czech Republic had shortages and that lead to like 5 different EV being produced in numbers far bellow announcement. With every car maker claiming to massively increase EV sales, those battery companies are standing to make huge money but they will capture much of the margin as well, because the battery is like 1/3 of the cost of the car.
The next generation drive train Tesla has announced for their S, X, Cybertruck and Roadster will blow out of the water even what you can get from a 200k Porsche Tycan. Nobody else has announced anything like it. Breakdowns of Tesla shows that their cheaper drive trains are both lighter and cheaper to produce then the competition (see Sandy Monro).
In terms of Self Driving, among OEM so far as I know they are the only ones that are building their own self driving computer. They costume design their own hardware solution including their own designing their own dedicated chip and software to run on those chips. Plus, their tight fleet integration of cars that already have the sensor suited necessary allows them to query the fleet and use driver to train the network. Also, these computers are pretty cheap and light to build compared to the hardware that is in a Waymo car.
There are other things like software updates, business model innovation (no franchise dealership) that other car makers struggle with. The franchises is specially important because those dealers make their money on servicing, so they don't want to sell EVs.
All in all its fair to say that they do have a lead on a number of fronts. The competition has been catching up slowly, but mostly because they stared from nothing basically.
I think their main advantage at this point is that they make batteries that are well over 200 watt hours per kilogram and they can make them cheap, whereas most other EV batteries are in the neighborhood of 150.
Are they really though ? You don't see Tesla being much more efficient than any other EVs so far ?