i certainly looked fitter four years ago than i do now despite having driven pretty much everywhere and smoked a good deal of drugs.
i had a physical job (chippy), went kiteboarding two or three times a week (very good work out for upper body, stomach and the legs – hurt a lot, too). i even drove to go riding, but rode a lot less than i do now.
now i just ride. i very rarely use the train when getting about locally. my legs are much stronger, my lungs are maybe better since i’ve stopped smoking, but i’ve deveolped some insulation around my waist and my upper body strength has pretty much all but disappeared.
i can ride all day long, but struggle to do one proper sit-up.
hopefully things will change come september when i start chippying again. hopefully there is a shit load of snow in winter so i can go snowkiting, too. that’d be nice.
so no, biking hasn’t made me fitter, IMO. it’s helped me retain a level of fitness i’d have otherwise lost since leaving the UK.