You've made the leap and tuned up your bike or bought an RTD pass. You show up at work with the glow of exercise and sporting a sweet new laptop bag, smirking when you hear your coworkers' tales of traffic. The romance ends, however, when you have a meeting across town at 10 a.m., and there's no bus close to your destination. Or you'll spend an hour on your bike in the heat of the summer day, showing up drenched and unrolling your sweaty pant leg. Enter OccasionalCar, a new Denver-based car-sharing program that offers car rentals on an hourly basis. Visit the website, enter the time you need transportation, and show up to pick up the car from its reserved parking spot. OccasionalCar is still growing. So far the service has three cars available in Denver, with the plan of adding one to two cars per month for the next several months in different neighborhoods. (Vote for your neighborhood via the website.) Here are a few rules for car-sharing: Who: Those with five years of driving experience, though there is a special program for students who qualify. Where: Cars are currently stationed near the Whole Foods in Capitol Hill (11th Avenue and Ogden); near the Logan parking lot between 18th and 19th avenues on Pennsylvania; and at the Barclay Towers in LoDo at 16th and Larimer. Cost: There is a one-time, $25 application fee to cover a driving-record check and to get an electronic key. Rate plans vary, but cars can be as low as $3.49 an hour and 24 cents a mile. Pets: You can bring your pooch as long as you transport the little fella in a pet carrier. Gas: OccasionalCar pays for gas, but if you drive the car to the point that it dips to a quarter of a tank, you're in charge of filling it. But every time you do, you'll get a $2 credit.