A bus off the road earns nothing. Over a ten-year life, parts availability affects your business more than almost anything else on the specification sheet — and it is the hardest thing to assess before you buy.

These five questions get past the marketing answer.

1. What do you hold in Australia, and where?

Not "we have excellent parts support". A list, and an address. If the answer is that everything comes from the factory, your downtime is measured in weeks rather than days.

2. What is the fill rate on a common service item?

Fill rate is the proportion of orders satisfied from stock without a backorder. Any supplier who tracks it will know the number. Any supplier who does not track it is telling you something by not knowing.

3. What happens when a part is not in stock?

Specifically: how do I find out, when do I find out, and do you tell me or do I chase you? A part that is late is survivable. A customer who discovers it by ringing is not.

4. How do you handle a warranty part?

Do I pay and get reimbursed, or do you supply it and settle with the factory yourself? The difference is real money sitting on your account for months.

5. Who supplies the running gear?

This is the most useful question on the list. A bus fitted with an engine and driveline from a manufacturer that already has a national Australian service network is a fundamentally different proposition from one with proprietary components.

It means any competent heavy vehicle workshop can service it, parts are available through existing channels, and you are not dependent on a single importer staying in business.

And one to ask yourself

If this supplier withdrew from the Australian market in three years, what would happen to my fleet? It is an uncomfortable question and worth answering honestly before you sign.