61. AUTOMATIC TRANSMISSIONS: What are the different types?

Torque converter automatic

The traditional type employing a torque converter that abosrbs engine power leading to increased fuel consumption and CO2 output.

Can be 2, 3, 4, 5, 6, 7 or 8 ratio, the more ratios the more efficient it will be.

May have manual override for which different manufaxcturers have different brand names, for example 'Tiptronic', 'Geartronic', 'Autotronic'.

The manual shifter may be a nudge forwards/backwards shifter on the quadrant, may 'slap' side to side (on Mercedes and Chryslers) or may have steering wheel button or paddle shifters.

Continuously Variable automatic
Shortenend to CVT and brandnamed 'Multitronic' by Audi.

This employs conical pulleys and steel belts to 'continuously' change ratios, now generally optimised at 7, which can be selected and held by the driver to a point if he or she wishes.

Audi, Nissan, Honda (in the Jazz) and Mercedes (in the A and B Class) offer CVTs. Nissan combines the CVT transmission with a torque converter rather than an electromagnetic clutch to take up initial drive.

CVTs are generally much more fuel efficient than Torque Converter autos.

Direct Shift Gearboxes

These is VAG's transvverse engine twin-shaft 6-speed manual transmission with a pair of oil clutches. Because the next ratio is always on the opposite shaft, it can be 'pre-selected' and changed to rapidly and efficiently, usually at no sacrifice in fuel economy. They work either fully automatically or with driver control by nudge shift or paddle. Audi has re-named DSG 'S-Tronic'.

Automated Clutch Manuals

These are really manual boxes with electronically controlled electric motorised clutches controlling the gearshifts either 'fully automatically' or by the driver using a shift lever or paddles. Employed in cars from Ferraris to Citroen C1s. Variously called M/M. MMT, F1, R-Tronic, Sensodrive, EGS, Easytronic, Durashift. Can be very difficult to achieve a smooth change from 1st to 2nd with these boxes. But they are getting better. The EGS in the new Citroen C4 and C4 Picasso is quite good. Can also bring benefits in fuel economy and C02 output,. The Citroen C4 1.6 HDI 110 EGS emits less than 120g/km CO2.