You got to remember that most trainers are .40 size mostly because that size is a tradoff between the advantages of small and the advantages of big. If you can afford a .60 size plane and the somewhat greater amount of fuel it burns and you drive a car that easily carries it to the field, then go for .60.

I haul a .60 size plane in a Geo Metro but that's about all I can carry to the field in that car.