as I said before possibly a good place to start is the Hagerty Insurance Valuation Tool possibly not what SP owners ( or even Mk1 owners
) believe their car is worth but a reasonable start position without the owner emotion added. Of course, as had been said before, in the end they are only worth what someone is willing to spend.
see
http://apps.hagerty.com/ukvaluation/ind ... Backlink=1" onclick="window.open(this.href);return false;
1972 Jensen Interceptor III SP
2dr Saloon
Values by Condition
Fair £21200
Condition 4: Fair
#4 cars are daily drivers, with flaws visible to the naked eye. The chrome might have pitting or scratches, the windshield might be chipped. Paintwork is imperfect, and perhaps the fender has a minor dent. The interior could have split seams or a cracked dash. No major parts are missing, but the wheels could differ from the originals, or the interior might not be stock. No major customisations have been made. A #4 car can also be a deteriorated restoration. "Fair" is the one word that describes a #4 car.
Good £32400
Condition 3: Good
#3 cars could possess some, but not all of the issues of a #4 car, but they will be balanced by other factors such as a fresh paint job or a new, correct interior. #3 cars drive and run well, but might have some incorrect parts. These cars are not used for daily transportation but are ready for a long tour without excuses, and the casual passerby will not find any visual flaws. No major customisations have been made. "Good" is the one word description of a #3 car.
Excellent £45600
Condition 2: Excellent
#2 cars could win a local or regional show. They can be former #1 cars that have been driven or have aged. Seasoned observers will have to look closely for flaws, but will be able to find some not seen by the general public. The paint, chrome, glass and interior will all appear as excellent. No excessive smoke will be seen on startup, no unusual noises will emanate from the engine compartment. The vehicle will drive as a new car of its era would. No customisations have been made. The one word description for #2 cars is "excellent."
Concours £71700
Condition 1: Concours
Condition #1 vehicles are the best in the world. The visual image is of the best car, unmodified, in the right colours, driving onto the lawn at the finest concours. Perfectly clean, the car has been groomed down to the tire treads. Painted and chromed surfaces are mirror-like. Dust and dirt are banned, and materials used are correct and superbly fitted. No customisations have been made. The one word description for #1 cars is "concours."
JOC Interceptor Registrar 
Anyway this matter of gas guzzeling keeps coming up when a nice Jensen is tested. Same driver wouldn't say anyfing about the next guzzeller he drives/tests. Kenny38 
.
