If a production Jaguar with this powertrain had been available, would you have purchased an XJ instead of the Karma? The range extender in the XJ is a 2.0L four-cylinder unit from a Range Rover Evoque -- itself a unit from the Ford Escape.
http://www.autocar.co.uk/car-review/jaguar/xj/first-drives/first-drive-review-jaguar-xj-e

Read more:Hybrid XJ yields impressive economy, but it's not yet confirmed for production launch
XJ-e hybrid's official fuel consumption is 87mpg
What is it?
We’re talking here about the most economical full-size saloon Jaguar has ever built, the luxurious XJ-e hybrid, which I recently sampled on public roads as part of Jaguar’s three-car, six-driver entry in the 2012 Future Car Challenge, a 63-mile all-roads economy test between Brighton and London.
Our experimental Jag trio, part-financed by the government’s busy and productive Technology Strategy Board, proved their potential by topping their class in the Brighton to London test, winning the award for 'Most energy-efficient luxury car — prototype' and a taking a new award for 2012, the 'Technical panel’s wward of merit'.
The XJ-e, officially rated at 87mpg with a CO2 output of just 75 g/km, is an advanced prototype Jaguar is developing in case the world’s luxury car buyers discover a taste for extreme economy. So far they haven’t; companies such as Porsche have had limited showroom success with their Cayenne and Panamera hybrids. Seems those who can afford big-price cars can stump up big fuelling costs, too.
http://www.autocar.co.uk/car-review/jaguar/xj/first-drives/first-drive-review-jaguar-xj-e
