Original sentence: In March 2008, the UK's Sunday Times published the report of a fuel consumption comparison that had been perfomed between a Prius and a BMW 520d.The comparison involved driving both vehicles  from London to Geneva, with both motorway and town driving.The results showed that the BMW was more fuel-efficient than the Prius, returning an average of  to the Prius's , over an extended journey
Edited sentence: A March 2008 UK newspaper's "real-world" test over , showed the Prius to be less fuel-efficient than a BMW 520d.The BMW is a more expensive vehicle using more expensive diesel emitting more smog causing pollutants.The test was done mostly at highway speeds, 75 mph, where the hybrid technology is known to be less efficient