While some 15-passenger vans *could* potentially reach speeds of 70-80 mph on a highway under ideal conditions, it's important to note that:
* Safety: Driving a fully loaded 15-passenger van at high speeds is significantly less safe than driving a smaller vehicle at the same speed due to increased braking distances and handling challenges.
* Legality: Speed limits vary by location, and exceeding them is illegal and dangerous.
* Manufacturer Recommendations: Always adhere to the manufacturer's recommended speeds and load limits.
Therefore, focusing on a safe and legal speed is far more important than achieving a maximum possible speed.