Your question was "Which engine is (more) powerful??? Cultus or Alto"
Some how the disussion deviated towards which car is faster.
The enigine is the pwoerplant of the car. In that context Alto has a more powerful engine than Cultus.
But what transfers that power to the car's wheels is the car's transmission (also known as tranny), of which your gearbox is a part of.
The more refined a tranny, the more power transferred to the wheels and more efficiently. That is the actual power made available to be utilised.
Cultus has a much better tranny than an Alto. But that difference is offset by Cultus's heavier body.
So on the street, I believe, it boils down to the man behind the wheels which determines which car will win.
I have a Cultus-VXL 2006, its on petrol and tuned for the same. I have commuted many times on the highway from (Karachi to Hyderabad) and I don't recall a single instance where I couldn't pass an Alto whenever I wanted to. However I have had a tough time with Cuores. I have been able to pass them on most occaissions but not as easily as I could an Alto.
Cuore has a superb tranny.
I am planning to buy another car and eventually retire my 20 year old (and trusted) FX. Its either going to be a Chery QQ or a Cuore or a Vitz (if I can save up the cash for it, the other two I can lease easily).
Cultus, if run with A/C off and on petrol, has a pretty good response. Especially in the higher RPM regimes. It is more of a long distance runner than a sprinter. It is easier to maintain higher speeds for a longer period on a Cultus than on an Alto due to better road grip and a more efficient tranny.