- High technology petrol engine approaches diesel economy
- CO2 still higher than comparable TDI
- Avoids penalties aimed at diesel emissions
Whether it's due to natural progress of technology, or significant advances to compensate for the backlash from dieselgate, Volkswagen's latest evolution of petrol engines looks rather impressive.
Taking the low-emissions marketing a step further, the 1.5 TSI ACT BlueMotion continutes VW's use of the 'blue' branding so often associated with diesels, yet is a 130hp turbocharged petrol four-cylinder. In common with many high output petrol engines launched recently, cylinder deactivation - once reserved for immense, thirsty V8s and V12s - minimises consumption during periods of low power demand.
Economy might be the motivation for this state of tune, however the Golf 1.5 TSI ACT BlueMotion is far from slow. A 0-62mph time of 9.1 seconds and top speed of 131mph are respectable for any car claiming 58.9mpg combined.
Volkswagen: It's Miller time(d)
Further improving efficiently, a 'micro-hybrid' mode allows zero consumption coasting, and the engine managment uses the Miller cycle for ignition for a more efficient use of fuel. By shortening the inlet valve duration, and increasing the compression ratio, fuel is burned more effectively - allowing the same power output for less fuel.
Making this possible is a variable turbine geometry turbocharger, a technology previously only found in high performance cars.
When coasting, a high capacity Li-Ion battery back provides energy for vehicle systems, and the gearbox is disengaged to minimise drag.
The 1.5 TSI ACT BlueMotion is available now in the Volkswagen Golf and Golf Estate, producing 110g/km of CO2 when paired with DSG for both body styles and manual Golf hatch, and 113g/km in the six-speed manual estate. Prices vary according to specification, starting at £21,505 for a three-door Golf SE 1.5 TSI ACT 130 BlueMotion with manual gearbox.