It would be a pretty rough commuter car, rough ride, tons of wind noise/vibration/general discomfort.
Doing a proper greasel setup takes a fair amount of cash or a bunch of time, just throwing roughly filtered grease in the tank will result in untold problems. You may get away with it for a while but it will eventually bugger something/things up.
Veg oil is also incredibly messy and difficult to clean up, it eats most rubber and smells terrible.
Having said all that, lowball the guy, turn up the injection pump and have some fun with the thing for a few months.