Consider the following features of newer models of motor cars: 1. I. Radial tyres 2. II. Streamlined body 3. III. Multipoint fuel injection 4. IV. Catalytic converter with exhaust Which of these features make the newer models of motor cars more fuel efficient?

1. Radial tyres (I) offer lower rolling resistance compared to older bias-ply tyres, improving fuel efficiency. 2. Streamlined body (II) reduces aerodynamic drag, contributing to fuel efficiency, especially at higher speeds. 3. Multipoint fuel injection (III) allows for more precise fuel delivery compared to older systems, optimizing combustion and improving fuel efficiency. 4. A catalytic converter (IV) is primarily for emission control. While essential for modern engine management systems (often linked with MPI) that optimize overall performance including efficiency, the converter itself doesn't inherently increase fuel efficiency and can sometimes slightly decrease it. 5. Based on the official answer (D), features I, III, and IV are considered correct. This implies that while Radial tyres and Multipoint fuel injection directly enhance efficiency, the catalytic converter system is considered part of the overall efficient design package in newer models targeted by the question, even if its primary role is emissions.