The figures quoted seem about right. Aircraft are two to three times less efficient than a car with 100% load factor. However this is generally a pointless statistic. You wouldn't drive to New York. And that's the problem. The aircraft is doing a 7000 miles round trip. Whether or not it is efficient is probably less relevant than whether it is ecologically advisable. To answer that it may be best to think in terms of gallons per hour.
Popping over to New York for a few days break, you're burning maybe half a tonne of fuel. Believe me - you wouldn't find that acceptable for 4 days in Scarborough.
Airliners are in general a nonsense. They only serve the following purposes:
1 Allow people to maintain a personal presence across large geographic territories rather than delegate responsibility.
2 Allow people to live in otherwise uninhabitable geographic areas (eg UK)and still enjoy decent weather now and again
3 Allow pilots to spend their lives avoiding the crushingly boring work that almost everyone else has to do.
Items 1 and 2 are entirely unnecessary. Item 3 keeps the whole thing going. Would you want to work in an office?