Imagine if a 13-year-old used a sewing machine one time. Then twenty years later, he tried to use a sewing machine that was thirty years older than the one he used before... It wouldn't exactly be smooth sailing.
A sewing machine might be a weird analogy, but it's just 'cause cars are so taken for granted these days. People think it's weird for Kirk to have forgotten how to drive, yet if you substitute a car for a different piece of machinery, one that's as obscure to most people today as a car would be in the 23rd century...
Even as a guy who both drives and sews, I can understand how Kirk would be so uncomfortable with a car after two decades without driving.