For me its very simple. If you refuse to trade votes (to put it bluntly) nothing will get through.
Stuff will get through even if GM will need to do some tie-breaking rolls for a dozen of one voted proposals
Some optimal stuff may not get through, yeah (see the last turn and fighter).
So what? You see, I hate any forms of metagaming. Trading votes is a blatant metagaming
You want to know why people don't vote for your engine? Then ask. If you noticed I tend to ask quite often why people don't support some of my ideas. Some thing that you may see as obviously useful, other people may see as quite bad
I am not voting for 9 because
1) In no way I want a new truck. If you noticed I am trying to get rid of truck production for several turns in a row. The only thing we could want heavy truck for - towing heavy guns, that we have none (160mm is too heavy to towed by any truck)
2) It's entirely possible to design new vehicles without designing an engine for them beforehand. In fact that's more logical way to do it, design engine that fits vehicle, not engine that you need to design vehicle around
3) We are not in great fuel situation, all diesel fuel should go to Herrings and Hunters....
4) I don't want fuel hungry powerful tank engines in general. We don't need fast tanks. We can't afford to produce heavy tanks. We need diesel fuel for the navy and petrol fuel for both airforce and navy (Our fleet of patrol boats eating way too much petrol, BTW. Cods are eating that too... As I said petrol engine is a bad thing for the sub. )
5) While I'd prefer to get new diesel engine for the navy, that means designing new maritime diesel not one fit for all engines
6) While that is metagamish in some way, I prefer to choose thing fun for GM to process, and fun for players to read the results. You got new (bad\OK\great) engine is not something I play this game for
A question on the tankette: We've still got several turns before an invasion is possible, during which we will have other, better tanks. I assume that the tankette is outarmoured and outgunned against their new tank models already. Do the advantages really warrant producing them now when we have other priorities?
a) Enemy may try landings again. They'll not bring much heavy guns with them so tankettes will be useful (even if easy target for their tanks) Furthemore, tankettes are fast to move where enemy has landed
b) I am not offering to build new factory for the Tankettes, that indeed is a waste. I am offering to switch half of the production from not that useful trucks.
c) Even later, due to their speed and range, tankettes will stay useful in scouting roles
d) Rebuilding them later as SPG or SP AA guns shouldn't be hard. It offers a good, fast chassis, quite cheap and made from local materials. Remove turret and top armor, and we have a base for any kind of light armored vehicle. Yes it will be heavier and thus slower, but with it's current great speed that is affordable, having a factory producing producing those chassis is nice because retooling is trivial