Opponents of plug-in hybrids include environmental groups, which call them "fake electrics," arguing that real-world driving of the cars result in much higher fuel consumption and CO2 emissions than promised from WLTP tests. Therefore, green groups says plug-in hybrids do not deserve to receive the big subsidies from governments.
Determining how much fuel is saved and how much CO2 is reduced compared with a fuel-powered car is tricky. The share of kilometers driven in full-electric mode depend on factors such as the utilization pattern of each driver, the availability of recharge points and how diligent the owner is about keeping the batteries full.
I'm the relatively new owner of a Seat Leon plug-in hybrid. I used the first 2,000 kilometers to answer questions such as: How much fuel and electricity did I really consume? How different were my results from what was promised by the WLTP figures?
Let's take out the calculator
The Leon's on-board computer shows the car's average fuel and kilowatt hour consumption figures at any time. At my chosen cutoff point for this exercise of 2,103 km driven, my average electric energy consumption was 6 kWh per 100 kilometers, said another way, that is 16.6 km per kWh. I used 83.51 liters of gasoline, resulting in consumption of 3.97 liters per 100 km. That means I traveled a little more than 25 km per liter. The car's figures were confirmed by my own calculations, based on how many liters I put in the tank.
These figures, however, do not reveal how efficient the car was during electric-only or gasoline-only driving. To verify those figures, I ran two short separate tests.
With a 12.8-kWh battery charged at 100 percent, the cockpit computer gives a 62 km range, or 4.84 km/kWh. I started with a battery charge of 86 percent (11 kWh). Before it got to zero I managed to go 47 km, mixing both city and highway driving. That is equal to 4.3 km/kWh , which was done under ideal weather conditions of 20 Celsius so I needed no air conditioning. That tells me the promised WLTP range of 60-plus km is quite attainable in city driving.
How about driving only using the gasoline engine? To do this I set the computer parameters to "no recharge" and traveled 153 km with zero battery. My test route was a third city driving and two-thirds motorway (at speeds of 90 to 120 kph). The result was fuel consumption of 5.5 liters per 100 km (18.2 km/liter).
I then cross-checked things a different way. At the rate of 4.3 km per each kWh calculated above, with the 167.26 kWh I put into the battery, the car has run approximately 720 km in electric-only mode. Subtracting that from the total driven, 2,103 km, results in 1,383 km traveled using 83.51 liters gasoline, or 16.6 km/liter. The latter figure was not as good as my test above (18.2 km/liter), most likely because of my higher average speed while driving on the highway.
The 16.6 km/liter figure is also very similar to what I used to average with my previous car, a 1.0-liter, three-cylinder gasoline seventh-generation Golf with a dual-clutch transmission.
That did not surprise me because my Leon's ability to recuperate energy while braking is offset by two factors: it weighs more than my old Golf and its more powerful 1.4-liter, four-cylinder gasoline engine uses more fuel.