system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can cars like the Honda CR-X get 52 mpg in 1984 but average cars now get the mid 30's?

Explain?
gpt
Weight and Emissions requirements.

Cars have progressively gotten heavier for safety reasons such as mandatory air bags, and higher crash test requirements.

Car engines also have much more restrictive emissions laws influencing their design. Things like catalytic converters affect horsepower and efficiency.