So here are
PASSO VS VITZ TECHNICAL DETAILS
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AC Compressor
Vitz has bigger AC Compressor, So it performs better than Passo. as AC Compressor pics Shared by @Nabeel_Ali Bhi...
Passo's AC compressor is smaller and somewhat similar/same as Mira ES...
So Vitz AC is powerful, may be it require more energy aswell
CVT GEAR BOX
Now Coming on to CVT GEAR BOX
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VITZ has bigger Gear Box with better Gear Ratios. Its design is definitely different than Passo's CVT Gear Box, As Passo has CVT Dipstick and Vitz doesn't have one...
On the other hand, Passo's Gear Box is same/similar to Mira as shown by Gear Ratios in Pic...
Result: Vitz Perform better with big gear (better gear ratio) box and 1kr engine than Passo with smaller gear box and 1kr
If u drive Vitz on motorway, it can go upto 160-170 km/h... but Passo can reach 120-130 km/hr, after that it will struggle to reach 140 or above... 160-170 is not possible in passo
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On these aspects Vitz should have better pick aswell
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Weight
Also weight difference.. Passo 910 Kg Vitz 970 kg
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Conclusion:
Passo is made for Economy and Mediocre Performance
Vitz is Powerful yet Economical (but a bit less than Passo)