I Have a Swift ZXi. I live in mumbai. I bought my car in March, and till date its clocked about +5k km's already!!.
This is the first time I read this post and thought would contribute my experience to this thread.
I just returned from another long trip this weekend, driving to and from hyderabad.
For the first ~250 km I drove sort of normally and as aggressive I could be to survive mumbai traffic
I had to go to hyderabad urgently then and decided to drive down instead of flying. I did a almost nonstop drive to Hyderabad overnight which I did in about 12~13 hours (720 km to hyderabad). In the first drive I couldn't push the car above 100kmph (i was a bit concerned about blowing the head too
) but i did average about ~80-90 kmph at the time. Since it was a night drive i dint have much traffic and it was a breeze. In fact I was pleased to have opted for ZXi with ABS as it did save my *** when negotiating a oncoming train of trucks, a trucker thought he could just negotiate an overtake when a car was hurtling at him at 100!! I hit the breaks hard at the time as i dint have a lot of place to negotiate along with blinking lights et al. In the hard braking, the brake pedal juddered as I safely negotiated away from a head-on!! (Had to stop immediately afterwards to calm my nerves and run down the excess adrenaline in my blood after that!!).
I checked the mileage turned out to be 17~18 kmpl in that trip.
Definitely after my return, i started to feel guilty of having pushed my car so hard for a long haul, but i did see perceptible difference in the car. In fact I am getting about 9~12kmpl depending on the day/traffic in city conditions. Although this i think is acceptable owing to the fact that the climate control is on all the time at ~23-25
In fact, the initial 250km were strained and I was wondering of where all the horses were!! But now the car is definitely more smoother and more responsive!!
This time, however after my second service (Got a second service + an oil change and filter change at my expense), I decided to drive again. Whoo boy was it a pleasure drive!! The car would sweep across 100 easily and I hit 140 kmph on the expressway with room to push it for little more at the pedal!!
I made it to hyderabad in 11 hours, and return i made it in 10 (actually 9hrs 40 minutes i was in Vashi)!!!
On the onward, it fetched me ~16-17 kmpl with climate control on 70% times, and return fetched me ~19-20 kmpl with 30% climate control (had to use it to defog the windshield in the rains!!) Thats simply amazing!!
I think although what MotoTune says is controversial, there is some truth in it. I dont agree factory engines need to be run-in so carefully as much as a rebuilt engine needs. In fact for a new factory engine always comes with enough clearances already set (imagine the number of siezed engines manufacturers would be fixing otherwise!!). However when the engine is rebuilt and pistons changed to oversize, the reboring is done for closer tolerances and needs more time to build back the running clearances.
In my college days I owned a Kawasaki RTZ, which I used to fool around with. I overhauled the complete engine nearly 3 times with my own hands in those days. It was notorious for seizures at high speeds!! I replaced the bore and piston and run-in needed then was lesser. It lasted longer (abt an year before the first siezure as the oil pump failed!!). Then i got a reboring done and had to do what they call as "Cooling": which is to leave the engine running for few litres of gas for the breaking in.
I trust MotoTune is ok with the idea of setting the piston rings, but I dont think there is a clear quantifiable method for this to be done without wrecking your engine for a layman as well. Thats the reason why manufacturers recommend a more conservative approach for running-in. For the moto-holics, yes the new car needs to be run-in a bit more aggressively.
From my experience, the first 250~300 km is the break-in period, and after that the run-in period starts where in you let the engine open up well.
As for my Swift, I luv it!!
Cheers