You gave answer to your quary, Fiat Gearbox is not same as Maruti gearbox, where in gear acceleration in first & second gear is better. Maruti is light weight so the pulling torque per weight is more than fiat. That is the reason you felt this. Case 1:- Take 3 kg weight in your hand and try to spin and take 5 kg and try, it is your same hand but spin will be less in 5 kg case. Case 2:- Sehwag has the breathtaking century and treat to watch ( FTD as Swift), but long term safety & secure century is from Sachin ( Sluggish but steady FIAT). So you may expect from Sehwag to built fastest score not the steady century, but steady & fast can be expected from Sachin. Both are different. Same Maruti & Fiat scenario.