A new type of race car debuts Monday in Las Vegas with the public unveiling of the Spark-Renault SRT_01E, a fully electric vehicle capable of reaching 150 miles (241 kilometers) per hour or more. The debut is a first glimpse of sorts at Formula E, an all-electric version of the hallowed Grand Prix racing circuit that begins this year in September in Beijing. For the inaugural season, all ten teams will run the Spark-Renault vehicle. (See related story: “Electric Cars Hit Milestone With First Grand Prix Race Ahead.”)
The new race has drawn celebrity support and international participation, with hopes that an electric Formula competition will boost fuel efficiency while adding an imprimatur of eco-friendliness to a sport not known for fuel conservation. But how do gas-fueled and electric race carscompare in terms of energy efficiency—one of the green selling points that has driven electric car growth?
The U.S. Environmental Protection Agency has developed a conversion formula to enable energy efficiency comparisons between gasoline vehicles and electrics such as the Chevy Volt and Nissan Leaf. The EPA standard equates 33.7 kilowatt-hours (kWh) with 1 gallon of gasoline (3.8 liters).
According to documentation from Formula E, the circuit’s new cars will run with a limit of 30 kWh, which is set by the governing body of international motorsport, the FIA. This limit is the most energy the battery system can deliver to the motor during an entire one hour race. At 30 kWh, that’s equivalent to less than one gallon of gasoline, using the EPA conversion. (See the full set of specs for the inaugural season’s Spark-Renault SRT_01E.) This compares favorably indeed to the race’s gasoline-fueled counterpart, F1, which averages three to four miles per gallon (mpg), or 1.7 kilometers per liter (kml).
Though they can’t approach the fuel efficiency of an electric race, conventional racing teams have been experimenting with cleaner-burning fuels. In 2010, the F1 race saw its first ethanol entry when Ferrari debuted, and won, a vehicle that ran on a cellulosic ethanol blend. Another racing franchise, IndyCar, burns a mix containing 85 percent ethanol, which does mean cleaner exhaust. (For comparison, most cars in the United States run on a blend of no more than 10 percent ethanol, the maximum they are designed to handle.)
However, IndyCar and other conventional races burn fuel—ethanol blend or not—in huge amounts. According to the IndyCar website, the fuel allotment for superspeedways like the Indianapolis 500 is 4 mpg for the race distance. That number includes pace and parade laps that get much higher gas mileage, so actual race mileage is likely only 2 or 3 mpg (.85 to 1.2 kml). But even using the higher 4 mpg figure, an IndyCar would burn some 125 gallons (473 liters) in a 500-mile race. Recent winners have clocked in around the three-hour mark, meaning their IndyCars would burn well over 40 gallons (151 liters) of fuel during the same hour of racing that costs a Formula E model the equivalent of just 1 gallon. On IndyCar’s 13 road/street courses and short ovals, the numbers are worse, with just a 3 mpg fuel allotment that again includes pace and parade laps.
Ironically, Indianapolis 500 history shows that past mpg performances were much higher. In fact, Clessie Cummins actually ran the 1931 Indianapolis 500 with a diesel waiver. The car didn’t win, but it completed the race without refueling, averaging a whopping 16 mpg (6.8 kml).
NASCAR, which introduced a blend of 15 percent ethanol to its races in 2011, says on its website that the switch “actually boosted the performance of the race cars in all three of NASCAR’s marquee series — lowering emissions and increasing horsepower.” But NASCAR, too, is a far cry from electrics when it comes to fuel efficiency. A typical model gets perhaps 5 mpg, and so might burn 100 gallons of gas during a 500-mile (804-kilometer) race. There is lots of variability due to different tracks and conditions, but the Daytona 500, for example, can last for three or four hours, meaning a NASCAR driver would use 25 or 30 gallons of fuel for each hour on the track.