Since Sunday’s announcement in Shanghai of the Cadillac CT6 plug-in hybrid, there has been some interesting discussion and speculation about how far the car will go on a full charge of its battery and what sort of energy efficiency it will achieve. Cadillac and GM officials have declined to get specific about technical details beyond the limited information in the U.S. press release. However, the release on GM’s Chinese media site lists 37 miles. Let’s take a look at where the EPA estimate will likely end up.
However, enough information is available to make some reasonable educated guesses. We know that the 18.4-kWh lithium ion battery appears to be a repackaged version of the energy storage system in the second generation Chevrolet Volt. The closest direct competitor to the CT6 that is currently available for sale, at least in Europe is the Mercedes-Benz S500 PHEV. Mercedes-Benz claims the S500 is able to go 33 km (20 miles) on a full charge of its battery based on the EU drive cycle which tends to provide some overly inflated results compared to the real world. When the S500 PHEV arrives in the U.S. in the coming months, it will likely get closer to about 13-15 miles on a charge.
The battery in the CT6 will have more than double the capacity of the S500, and significantly less weight. The big German weighs in at close to 4,900 lbs. The base version of the CT6 with the same 2.0-liter four-cylinder engine used in the hybrid is expected to weigh about 3,600 pounds. The battery pack should add a bit less than 400 pounds and other items like the hybrid transmission and charging system will likely add another 100-200 pounds for a total weight likely to be 4,200 pounds or less. For comparison, the much smaller ELR coupe tips the scales at 4,050 pounds and has only 17.1 kWh of battery.
Chevrolet is claiming the second-generation Volt will go 50 miles on a charge from the same battery capacity as the CT6. With the improved efficiency provided by GM’s new motor designs, lighter weight and more than double the electrical capacity, it’s not at all unreasonable to expect that the CT6 will be able to go at least twice as far as the Mercedes or more than 30 miles. The ELR is currently rated at 37 miles per charge and in Mike Colias of Automotive News reported on Sunday that CT6 would match that. It’s probable that the CT6 PHEV will be able to go around 32-34 miles on electricity.