The Jaguar XJ has evolved in a very conservative manner since the debut of the Mark X sedan all the way back in 1961, but the big cat is poised for its biggest transformation yet as it becomes an EV, Autocar reports.

According to the British publication, the XJ will now reportedly be fully electric like a Tesla and feature a five-door instead of a four-door layout.

The next-gen model, due to be unveiled later this year ahead of 2019 sales, is being developed alongside a more car-like Range Rover model known internally as the Road Rover. Autocar reports that design work has been completed under the leadership of design boss Ian Callum and that the design has been well-received within the company. The switch to a five-door layout, according to Callum, arose from the unexpected acceptance of the fastback/hatchback bodystyle in the U.S. thanks to Tesla.

The reinvented XJ will reportedly have an aluminum architecture and offer all-wheel drive. Autocar reports that the sedan will have a range in excess of 300 miles on a full charge, which should make it competitive with other EVs that will be on the market in 2019. Don't expect a gas-electric hybrid early on -- Autocar says that a hybrid version may not even materialize as Jag does not want to dilute the impact of the marque flagship becoming an EV.

This is a lot to take in, admittedly, since the XJ has always been a stolid, cozy, gasoline-drinking sedan with four round headlights, a dusty tome of Sir Ernest Shackleton's exploits in Antarctica, a fireplace, a bear skin rug and plenty of lacquered wood bits. Even before the new model arrives, we're already feeling nostalgic for a time when the XJ could be counted on to be all those things.

At the same time, we can see why Jaguar wanted to reinvent the XJ entirely; no previous generation could make a sales dent against the S-Class/7-Series/A8 trio, and the arrival of large sedans from Lexus, Infiniti, Acura and others hasn't made its share of the pie any bigger. The traditional four-door sedan is also on a decline at the moment, as the industry slowly rotates to large crossovers, SUVs and electrification. Going fully electric with its flagship this early on will be a bolder step than many of its competitors plan to take in the near future, as they hedge their electric strategy with parallel lineups.

Time will tell if this is a brilliant move on the part of Jag -- or one that overestimates the immediate demand for electric luxury sedans. EVs currently make up less than 1 percent of new car sales in the U.S., and among that one percent there are plenty of Leafs and Bolts before we get to the full-size luxury sedans like the Tesla Model S, which the Jag XJ will have to battle right out of the box. That's a pretty small slice of the pie at the moment, and it will take a major, unforeseen shift for EVs to get to merely 2 percent next year.