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With a higher torque rating the car will generally make more power at low rpms and get you moving much faster where a car with lower torque and higher horse power will be slower to get moving and make up for it at higer rpms.
With more torque you will have more of a muscle car type feel with power right off the line. With less torque you have to get high rpms to get into the power band.
For example a high torque engine migh make max horse power at just 4,000 rpm where a low torque engine has to be near redline to make max power.
Yes more displacement generally makes much more torque. Torque will not generally have a big affect on top speed as it is all in gearing and transmission. As far as passing torque is what helps there as you don't have to get the rpms way up to get into the horsepower.
Potential is shown by torque, you can make a honda make a lot of power but it has limitations, but look at a 500 inch top fuel engine making 8,000 horsepower and the potential is clear.