I've got a '79 and an '81 and the one real problem with them is that they are generally driven much harder than the "normal" 240s, so overall general wear rate is higher. Check for worn/broken suspension bushes, worn brake rotors, gearbox (hard shifting and/or noise in neutral with clutch engaged), proper overdrive function (should engage/disengage quickly and silently and ,provided the clutch is used when engaging/disengaging it, smoothly) and any other normal wear and tear items (heater fan motor for noise/proper function, coolant leaks in cabin from heater, smokey engine on startup and after periods of idling, vibrations from driveshaft, shock absorber function, etc. etc.)

They have much better handling than the standard models; higher grip levels, much less body roll, but slightly harsher ride (especially '80 on) due to slightly stiffer springing and much thicker sway bars. I love 'em!

Fuel consumption will vary a lot with driving style, engine condition, tyres, etc., but expect an average of about 11 litres/100 km or better for an equal mix of city/highway driving if the car is in good condition. Cheers