Already 5000+ KM ?? Man, you are catching up fast on the ODO...
Btw, take a look at my
thread (Swift Diesel Ownership Review after 600 KM), already crossed 12000 KM on my Swift LDi. The 10k KM service cost was very decent and the car feels silky smooth after that.
On the top speed front, I went little over 165 KMPH and I doubt if there is a speed limiter inplace. I constantly drive at 130-145 on highways and still manage to get a 20KMPL mileage.
But beware of the brakes, they are not great on stock tyres especially after 140 without ABS, EBD, etc.