I would love a petrol voucher. 90% of Australians have a car so it would be useful to pretty much anyone's family. It's also a somewhat inelastic good, meaning if I gave you a petrol voucher you probably wouldn't considerably change your driving habits. Maybe you would use it to go on an extra family trip, which yes gasoline bad, but it's not exactly conspicuous consumption. It would just give you some extra money in your pocket. I would much prefer that to something like a vacation voucher or a new car or some useless stuff that I wouldn't pay my own money for.