ILLYA VERPRAET
Testing, testing
A new and fairer way of testing PHEVs’ efficiency is a good thing, right?
Both of our road test subjects this week are plug-in hybrids. According to the official WLTP figures, one does 256.8mpg, the other 282.0mpg. A Volkswagen Passat eHybrid even boasts 731mpg. There is some sense to these numbers. The way they come about involves something called a ‘utility factor’, which represents the proportion of total miles that a PHEV is likely to drive in electric mode – when it uses no fuel at all.
The actual numbers are furiously complicated, but in effect it boils down to this: if a PHEV with an electric range of 48 miles starts a 50-mile journey fully charged, then it will indeed use a minute amount of fuel. These figures are achievable if you religiously plug the car in and rarely do journeys that exceed the electric range.