Sure, but a bus lasts 12 years in service (depending on use slightly different, but 12 is a reasonable number for discussion). You should be buying them on a l

Sure, but a bus lasts 12 years in service (depending on use slightly different, but 12 is a reasonable number for discussion). You should be buying them on a longer contract to deliver 1/12 of your total fleet every year for several years. This means that you only need to ask what to train the mechanics on at the end of the contract and in turns there are not that many different buses you need to train on. Keeping the same manufacture does reduce training costs some, but it isn't like every bus is different. Even ignoring the above, all but the smallest agencies can dedicate mechanics to each make. A mechanic can maintain so many buses per year - lets say 10 for discussion (I have no idea what the real number is), so if you have 100 buses you need 10 mechanics. if you have 4 trained on brand A, 4 on brand B, and 2 on both you are fine.