It's true of all 'sub-models' of a given make and model.
Consider the BMW G20 3-series petrol cars. Essentially all trims except the M340i have twin-turbo 2-litre inline-4 B48 engines. The engine output is tuned by the engine control unit (ECU, which is a bit of software running on an embedded computer) depending on the trim: 318i gets 115 kW, 320i is 125 kW, 330i is 190 kW. There are occasional hardware differences—typically the intake manifolds, radiators, and maybe belts, but the engine block is exactly the same across these trims—they're all B48. This is public knowledge; there is a detailed table on Wikipedia[1].
Engine 'tuning' is exactly tweaking numbers in the ECU. A stage 1 tune could involve mapping a 318i to a 320i or better without even popping the bonnet; just a laptop plugged into the OBD2 port above the driver's foot rest.
Naturally, as mentioned by others, some of these tunes are less than legal, because the price, road tax, and other legalese surrounding motor vehicles are determined by the performance and fuel economy of the vehicle from the factory. A car is so computerised that nowadays there are plug-in 'chip tuners' that remap the ECU signals on-the-fly and just-in-time, and can be removed before inspections. It's not dissimilar to overclocking computer chips.
This applies across all car makes, not just BMW and not even just European ones.
Intake and exhaust manifold shapes affect the power and torque characteristics of the engine. Also, these are not cheap parts. Also a quick glance at the parts catalogue suggests that the example engine, BMW B48, has different pistons and connecting rods for different tune levels, suggesting that the cast engine block is one of the few components which are actually interchangeable between the versions. Didn't check, but I'd guess the turbocharger compressor and turbine wheels might be different, too.
Consider the BMW G20 3-series petrol cars. Essentially all trims except the M340i have twin-turbo 2-litre inline-4 B48 engines. The engine output is tuned by the engine control unit (ECU, which is a bit of software running on an embedded computer) depending on the trim: 318i gets 115 kW, 320i is 125 kW, 330i is 190 kW. There are occasional hardware differences—typically the intake manifolds, radiators, and maybe belts, but the engine block is exactly the same across these trims—they're all B48. This is public knowledge; there is a detailed table on Wikipedia[1].
Engine 'tuning' is exactly tweaking numbers in the ECU. A stage 1 tune could involve mapping a 318i to a 320i or better without even popping the bonnet; just a laptop plugged into the OBD2 port above the driver's foot rest.
Naturally, as mentioned by others, some of these tunes are less than legal, because the price, road tax, and other legalese surrounding motor vehicles are determined by the performance and fuel economy of the vehicle from the factory. A car is so computerised that nowadays there are plug-in 'chip tuners' that remap the ECU signals on-the-fly and just-in-time, and can be removed before inspections. It's not dissimilar to overclocking computer chips.
This applies across all car makes, not just BMW and not even just European ones.
[1]: https://en.wikipedia.org/wiki/BMW_3_Series_(G20)#Petrol_engi...