No, a standard car cannot drive on a tree lying on the road. Attempting to do so would likely cause significant damage to your vehicle's tires, suspension, and undercarriage. A tree is a large, solid, and irregular object that acts as a formidable road obstruction, not a drivable surface. The primary safe response is to stop and find an alternative route.
The physics involved are straightforward. Your car's tires are designed for pavement, not for gripping and climbing over rough bark and uneven branches. The undercarriage, which includes the oil pan, exhaust system, and fuel lines, is vulnerable. Driving over a tree could puncture these critical components, leading to leaks, mechanical failure, or even a fire hazard. The suspension system, built to absorb bumps in the road, is not engineered to lift the entire vehicle over such a large obstacle, potentially resulting in broken springs or shock absorbers.
If the tree is small enough that you believe your vehicle, like a high-ground-clearance SUV or truck, might clear it, extreme caution is still required. You must first assess the situation safely. Check if the tree is stable and not hiding other hazards like downed power lines. Even with a capable vehicle, the risk of getting high-centered—where the chassis of the car rests on the obstacle, leaving the wheels off the ground—is very high. This would leave you stranded.
The only safe and recommended course of action is to treat a fallen tree as a complete blockage. Stop your car at a safe distance, turn on your hazard lights, and call local emergency services or the department of transportation to report the hazard. They have the proper equipment to remove it safely.
