all vtec is really is a smart head valve train set up, variable valve timing, when u get to certain rpms or ur ecu recognizes the conditions where you would want more power the camshaft slides over slightly and rolls over to larger lobes on ur camshaft cranking more air and gas into the engine, while maintaining good gas mileage at lower speeds. with a zc you can simply upgrade ur camshaft to one with more agressive lobes on the camshaft and you can push the extra hp out of the engine, but not without a loss of fuel economy, you'll just be pushing more air and fuel all the time, so you may have more engine wear... but... thats the situation, honda has great engineers that are able to crank out both high power when the situation presents itself while maintaining a great economy car, cuz im sorry go say guys our honda's are ECONOMY cars.