Very impressed with gas mileage

I’ve owned several A and B body Chryslers. All with small blocks. I just bought a superb condition, 2 owner 72 Scamp with a slant 6 with 60k original miles. I just returned from a 200 mile trip with that Scamp and averaged 28 miles per gallon !!!
If I add the mileage my truck gets, to the mileage my wife's car gets I don't think I'd hit 28

Of course, neither one of those are slanties.