My 12-mile commute to work includes multiple traffic lights and roundabouts which create traffic jams and offer plenty of opportunities for the Passat’s stop-start system to kick in.
Volkswagen’s technology runs off the main battery rather than a secondary unit but it is still pretty good. It operates in most temperatures once the engine has warmed up, unlike some we’ve tested recently which dislike any Celsius figure beginning with a negative.
Manually over-riding the system for the duration of the journey results in a noticeable dip in fuel efficiency – I reckon the stop-start is saving me at least 2mpg on the average figure by reducing idling time.
That means 49mpg rather than 47mpg on a comparative journey, which tots up to a monthly saving of £1 solely on my commute – or £12 over the course of a year. Considering I actually travel four times that distance over the course of a year, stop-start alone is saving me almost £50 (possibly more thanks to the M25!).
A fleet of 100 cars reimbursing actual fuel used could therefore expect stop-start to shave £5,000 off their overheads.
Another feature on the Passat did not perform so efficiently: cruise control. On a recent round trip to Luton – 54 miles each way – I selected cruise control set at the 70mph speed limit for the A1, A421 and M1 roads which accounted for the majority of the mileage on the out journey.
The resultant average fuel consumption was 53.2mpg.
For the return journey, I disengaged cruise control, but still kept to the speed limit using my own driving skills. Fuel consumption was 59.9mpg – a saving of 6.7mpg.
However, both figures are still relatively inconsequential when compared to the impact of the driver. Enthusiastic driving of the Passat easily drops the fuel efficiency to 38mpg; in contrast, ultra conservative driving tops out at 54mpg. I’m still failing to hit the official 61.4mpg, although we’re only just moving into four figures on the odometer - the engine should be loosening up soon.
The difference is worth around £1.40 a week - or a litre saved - on the 24-mile daily commute alone. Based on 25,000 miles a year, eco driving versus ‘enthusiastic’ driving (note - not dangerous or aggressive, just hard acceleration to get to the legal speed limit) saves £292.
Added to the stop-start saving, that’s equivalent to a pay rise of £450 for the driver; for the 100-car fleet it cuts the fuel bill by more than £30,000.