Plenty of ways to get a few more miles per gallon out of any vehicle: keep the tires inflated and engine tuned correctly.
Actually, thousands of people have died in car wrecks that needn't have because of EPA efficiency/pollution standards that forced the manufacturers to create lighter vehicles.
So we have more efficient fuel-consuming autos at the cost of many lives? Worth it? I don't know, you ask them.
BUt the idea we don't have environmental standards is nonsense. Maybe you mean lack of uniform standards?