OK, I guess I will play with these a little. I am not a fan of tapping for anything, and it's the reason why I thought Cohort was a terrible ability. But as a true Johnny deckbuilder, I like to play with all the cards, even the ones that don't appeal to me. (Solitaire, of course, there's near zero Vintage play online, and almost absolutely zero casual Vintage play)
Vehicles require you to have creatures you have no need for, except for tapping them to attack with vehicles. That is inherently a sucky strategy. Now you are using two cards to get something out of one of them. Yes, the vehicles are good attackers once crewed, but not that great.
Why would I want to tap my Wurmcoil Engine?
Vehicles don't enable other artifacts or other anything. They are only a resource sink.
I certainly plan to use Bomat Bazaar in battlecruiser Standard. It draws me a card!
Crackdown Construct is solid. It gets buffed every time I crew a vehicle.
Here is another example of Crackdown Construct getting buffed.
Here I am using Merchant's Dockhand to Scry 4. It is one very costly Scry 4, yet it is a Scry 4.
Oh, I get to buff Crackdown Construct. Not bad!
I get JTMS with my Scry 4.
With Daredevil Dragster I can attack twice, sacrifice it, and draw two cards.
Untethered Express is great. If I can play it well, it gets +1/+1 every time I successfully attack with it.
Here is the trigger for another counter.
In conclusion, I don't see why I would want to play vehicles in any other format than Standard. I feel that this is a missed opportunity for these cards.
Next day update: but I am not being true to my nature as a Johnny Deckbuilder. I DO want to try vehicles in other formats. I got me these now that they have fallen off standard (Smuggler's Copter is banned in Standard).