I just got my E type a couple months ago so I am still working on learning how everything works. The last few times I have filled the tank the mileage comes out between 12 and 13 mi/gal on premium fuel. That seems really low to me. I have seen posts here and there telling about normal mileage in the range of 20-25.
So, the question is, are there some easy and obvious places to check first to see why the mileage is so low?
It supposedly was all tuned up before I bought the car, but maybe they didn't do such a great job, and maybe it just needs the carbs to be properly tuned?

'69 2+2 4 speed manual 19K miles factory air.