F = G M₁ M₂ / R²
G = 6.67 x 10⁻¹¹ m³ / kg - s²
Without units . . .
1 = (6.67 x 10⁻¹¹) (900) (80) / R²
R² = (6.67 x 10⁻¹¹ x 900 x 80)
R² = 4.8 x 10⁻⁶
R = √(4.8 x 10⁻⁶)
R = 0.0022 meter
R = 2.2 millimeters
The man's center of mass has to be 2.2 millimeters from the car's center of mass. The car's center of mass may be somewhere in the back seat, but the man's center of mass is inside him, behind his belly-button. So the whole thing is pretty much impossible.
