With the addition of cars, I'd be excited to see motorbikes, or even just plain bicycles. Here are my ideas on the subject:
Bicycle- a human powered vehicle that simply requires human endurance and occasional maintenance, though most of the time even slightly rusty bikes with serve you well, as long as the teeth on the chain don't bust. Has increased mobility over cars but decreased speed.
Motorcycle- combines the speed and noise of a car and the mobility of a bicycle. The only negatives with these are noise and the amount of practice it takes to be any good with one. (which brings me to my next point)
Riding skill- someone who has ridden a motorbike will tell you, it is a skill. Someone who has never rode before won't be able to just hop on a bike and run away with any speed or grace. It takes practice. Lower skill should cause lower speed and maneuverability, possibly (though as it would aggravate players would be better served as a sandbox setting) stalling out your newly acquired 'iron horse'
Riding gear- these are the ideas I have on clothing added along with bikes
Motorcycle helmet- offers head protection and negates head bites and scratches, but would make everything a little bit darker, making it difficult to use at night unless you had a light of some kind (headlights, flashlight, outdoor porch light, street lamp, etc.)
Bicycle helmet- as above, except less protection and no drawbacks
Leather jacket, legs, and boots- all offer protection against bites and scratches, as well as some armor
Saddle bags- not always in bag form (the ones I've seen are thin metal crates strapped onto the bag and side) the offer storage, usually for tools or other equipment
This is what I've got. If you have any other ideas or concerns, please comment below. And as always, thanks for reading.