Does paying more money for parts increase performance?

Just putting out a growing suspicion which may be wrong, however when you come to making offers to suppliers (engine, fuel and tyres) you have multiple options to offer different amounts of money. The price that is already showing is a price that doesnt get rejected, you can also make a lower offer if you have good reputation; now this is where it gets intresting, as you can offer a lot more money than you need to for the parts. Is it possible that by doing this you can get more performance out of them? If not then why is it possible to offer a ridiculously more than what is needed? What purpose does that serve?

I'm a naturally suspicious person, so it may be total rubbish, however if you look deep into the game there are elements hidden from players which have an impact, such as the hiddden attributes of drivers, supposedly making the game fairer to stop the same people from winning all the time. I personally don't agree with this as it just makes the visible drivers attributes unreliable. 

What I may really be asking is, are there any other hidden elements that really shouldn't be hidden? 

The price suppliers agree to depends on the relationship you have. If it's bad, you will probably not even get them for the "standard" price and if it's average you won't get them for the low prices. Getting a bad relationship is mostly caused by breaking off contracts and forgetting to close the deal in time but if you want them anyway, you will have to dig deeper in the wallet.

Aside from that, the price of what you pay goes down after each time you extend the contract and i'm not getting bad engines from paying Murk under 200.000 each race. :)

I don't think the hidden attributes are a bad thing. It will not give huge differences in performance but just give more variety to drivers that seem to have similar statistics. Drivers tend to be good at certain tracks, sometimes they have off days and some are even bloody good when not having the maximum talent level and so on. I had my share of drivers over time and many of them were good but they all had their own way of being good. Seems pretty realistic to me.

There is no skeletons in the closet & no ghosts in the walls & no monsters under the bed. It don't matter if your driver has red, blue, purple, or green blood what you see is what you get. Different weight & height drivers work better on different tyres & fuel loads, that is what makes you think there is hidden statistics.

Paying out more does not equal more speed suppliers or drivers.
 

I understand how weight has an affect on speed but height? Could you explain? 

well, height probably doesnt really affect it much. Perhaps aerodynamically

Experiment and see :)
Short light drivers cant seem to get hard tyres to work, tall light drivers can.
Tall heavy drivers cant get supers to work, short heavy drivers can.