Abstract
Smeed's Law suggests that as motor vehicle ownership increases, death rates per vehicle decrease. The principal claims of the credit for this decrease are considered safer vehicles, safer roads and safer road users. The fact that Smeed's Law applies both to individual countries over time, and to collections of countries at any given point in time, suggests that safer vehicles cannot be given any credit for the decrease in death rates over time. The explanation which appears to account best for the available data is Wilde's risk homeostasis hypothesis.