the city is crowded by cars and especially motorcicles. I think so is whole Italy. Just read an article about rome: something about 200 000 motorcicles every day in rome downtown. Incredible!
If you can decide, better go by bus, train or plane to italian cities, it´s less stressful.
There sa reason why Verona is packed by sccoters and bikes...
You avoid the trafic, spare A LOT of time when crossing the town, park nearly everyway (and there are a lot of dedicated parkplaces) and, most of all, enter the historical city center. NO LIMIT for bikes, no matter if big or small, so you can park just a few meter from Piazza Erbe or Piazza Bra.
An excellent way to go around.
In the picture, a long row of scooters along Corso Porta Nuova... There is mine, too!
P.S. The only scooter rental I found online (no direct knowledge) in town is this one
If staying in the outskirts of Verona then vespa is the best transport way to get into the city center. Besides being easy to drive and makes its way through the traffic jams, scooter's big advantage is the easy way of parking and finding free places. It cannot be of big use inside the historic core of Verona because it is non traffic area, but scooter could be very helpful to reach some distanced sights.
I see no better means of transport for exploring area of Lago di Garda or surrounding places than scooter could be.