If you are flying into Aspen, you can rent a car from Alamo or National at the airport.
The hardest part about driving in the High Rockies is keeping your eyes on the road. A glacier-carved canyon off to your left, a soaring mountain ridge to your right, and there, standing on the shoulder, a bull elk. Some of the most scenic routes aren't necessarily the most direct. In summer, the 160-mi, three-hour drive from Denver to Aspen is a delightful journey up the I-70 corridor and through the Continental Divide at the Eisenhower Tunnel (or over the slower, but more-spectacular, Loveland Pass), down along the eastern ramparts of the Collegiate Peaks along State Highway 91 and U.S. Highway 24, with a final push on serpentine State Highway 82 up and over 12,095-foot Independence Pass.
The scenery, particularly south of Leadville on U.S. 24, is among the best in Colorado, with western views of 14,433-foot Mount Elbert, the highest mountain in the state. Independence Pass is closed in winter (timing depends on snowfall, typically late October-late May), but motorists should always drive cautiously. Blinding snowstorms—even in July—can erase visibility and make the pass treacherously icy. Be especially careful on the western side where the road narrows and vertigo-inducing drop-offs plunge thousands of feet from hairpin curves. Both Route 82 and I-70, like all Colorado roads, should be driven with caution, especially at night when elk, bighorn sheep, and mule deer cross without warning.
Generally speaking, driving to Aspen from Denver in winter is more trouble than it's worth, unless you plan to stop along the way. The drive west on I-70 and east on Route 82 takes more than three hours at best, depending on weather conditions and increasingly, ski traffic. On the other hand, the 3-mi drive from the Aspen-Pitkin County Airport is a breeze along the flat valley floor.
Colorado Road Condition Hotline (303/639-1111 near Denver; 303/639-1234 statewide). Colorado State Patrol (303/239-4500. www.csp.state.co.us).