Users of some online video watching services like Hulu and other media may have recently seen an advertisement where an anthropomorphic electric outlet smiled at a 23, with 8-11 flashed underneath. The company behind the commercial recently revealed the explanation, and it could spur interest in used hybrid cars in New Jersey.

General Motors said that the 23 and the plug actually represent 230, the miles per gallon that the 2011 Chevrolet Volt is expected to get when it is tested by the EPA.

There happens to be a slight catch for anyone looking to drive the car for any great distances, however.

“The key to high-mileage performance is for a Volt driver to plug into the electric grid at least once each day,” said Fritz Henderson, GM’s CEO.

What that means is that the car will have to be charged every night, and can only run 40 miles before the gasoline generator kicks in, according to the company.

Buyers looking for a fuel efficient car that maintains efficiency over a longer period may want to take a look at a used Toyota Prius in New Jersey, instead, with models offering better than 50 MPG and no tethering to outlets.