Mate - My knowledge of cars and specs is good.I am just not familiar with the E numbers when referring to BMW's as I don't particularly have much interest in them. However a quick look
here has helped me a little.
Now, talking from experience (my work colleague had an E36 M3 280bhp, an E36 M3,Evolution, a Z3M Coupe 321bhp and only recently sold her E46 M3), and having driven them all, I know there is no way a a car like yours would look near, certainly the E36 Evolution or the E46. Period.
Perhaps your car may keep with the 280bhp E36. Any expectations after that are misguided my friend. I spent some time looking for the 0-60, 1/4 mile time etc for this car and could not find a result which showed it to be slower than my car.
This brings me nicely to my next point. My modifications are irrelevant to this as I am not claiming my car can keep up with and beat M3 BMW's. However, I cannot see any Leon Cupra in
this list being faster than my Toledo over a 1/4 mile.
In my opinion, you are trying to convince yourself that your car is faster than it is - especially when comparing it against more similar cars. BMW's aside for a moment, there is absolutely no way your car would keep with a 300bhp Astra VXR. This claim on its own is bullshit.
As BenCTR said above, if you do keep up with these cars, it is possible the drivers in these other cars cannot drive very well, or when you think you are trying them on, they are not aware of this fact.