Audi has added a start-stop function to the automatic transmission version of the A3.
The new 1.4 TFSI petrol and 1.6 TDI versions of the A3 equipped with the S tronic twin-clutch automatic transmission will feature the new technology, together with a recuperation system to harness braking energy.
The A3 1.4 TFSI S tronic with start-stop is 3.7 mpg more economical than the manual option in the combined cycle economy test, recording 53.3mpg compared to 49.6mpg. CO2 is therefore also reduced at 124g/km, versus the manual version’s 132g/km.
However the car also reaches 62mph from rest 0.1 seconds more quickly than its manual counterpart at 9.3 seconds.
In its newly developed form for automatic applications, the start-stop system cuts engine power when the car comes to a standstill at traffic lights or in queueing traffic – the engine then remains dormant as long as the brake pedal is depressed and then restarts in just two-tenths of a second only when it is released in readiness for take-off.
With the system’s help, economy is boosted and CO2 is reduced by approximately 5g/km, but if required it can be deactivated at the touch of a button.
Recuperation technology provides further fuel and CO2 savings by recycling a proportion of the wasted kinetic energy generated under normal braking and normally dissipated as heat. This captured energy is stored temporarily in the vehicle battery to reduce the engine load when the car subsequently accelerates again. With its help, the A3’s fuel usage is reduced by as much as three per cent.
Electro-hydraulic controls and the alternate use of two clutches enable the S tronic gearbox to deliver extremely fast automatic or manual shifts via the gear lever or steering wheel-mounted paddle controls with no interruption of the engine’s power delivery across seven ratios.
The first of the two clutches serves the odd-numbered gears and reverse, and the second the even-numbered gears, so when the A3 is travelling in third gear, for instance, fourth is already pre-selected in anticipation. As soon as the shift command is given, the first clutch is disengaged and the second engaged in just a few hundredths of a second, virtually seamlessly.
With or without the S tronic option, the A3 1.6 TDI remains the most economical and efficient model in the Audi range, with a combined economy figure of 67.3mpg (manual 68.9) and CO2 output of just 109g/km.
The new 1.4 TFSI petrol and 1.6 TDI S tronic models are priced from £18,300 and £18,905 respectively.