Your 2000 i30 weighs about 3400 lbs. With 226hp (it's lost power since then), it's left with a power/weight ratio of 226/3400 = 0.066.

Despite the lower displacement, and lower power of the civic, it weighs about 2800 lbs, leaving it with a power/weight ratio of 180/2864 = 0.064 which isn't that far off from the i30.

The difference is that the i30 is a lot older and has definitely loss some of its efficiency with engine wear. Newer cars are also a lot more efficient than they used to be and are able to extract higher HP while maintaining reliability and improved gas mileage. The civic is able to maintain a close power/weight ratio, while getting 10/11 improved mpg, while reaching peak HP at a lower RPM (5500 vs 6400).

Assuming all else is equal, higher horsepower simply means the car has more power at a given RPM. There's a lot more that goes into the acceleration of a car than its peak horsepower at a given RPM. If you never reach 6400 RPM you're not actually making use of that 226 HP.