Be happy it is that sweet smell 
. Usually the sweet smell does not mean mold, just old dirt and dust.
There are worse ones:
The mechanic smell- dirty, greasy, fuel like an old mechanic’s shop.
The wet animal- This one ranges from wet dog to wet Billy goat.
The Dirty Feet smell- It smells like smelly socks that need to be bleached.
The ashtray- stale cigar or cigarette.
My new to me 1995 dodge smelled like the dirty ashtray in a 70’ s mechanic shop combined with man and dog that both needed soap. It was truly gag worthy. My 1995 Land Cruiser smelled like vomit and dirty underwear.
In the case of the Dodge we did the cursory alcohol spray, (rubbing alcohol or Vodka) put in a spray bottle, spray all surfaces until damp, shut the windows and leave in the sun to dry. This will help quite a bit. I usually follow up with a cloth bag of coffee or laundry scent crystals.
A good vodka spray and wipedown is pretty compulsory for all vehicles here, keeps them smelling fresh, kills most biological smells and is safe on the fragile interior parts of older/classic cars.
Of course my liquor store thinks I am a lush and I only do the Vodka treatment when I am not going to drive it. It can smell like a cosmo until until all the alcohol evaporates, 
Give it a spray, if it has seat covers, pop them off and throw them in the wash on gentle, air dry and reinstall. I actually prefer coffee, smells nice with the heat on…
