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The last 14 points in Acc

Until recently the design range in Elite was 0-100. Jack confirmed a long time ago that the simulator couldn't work with values greater than 100 so it is a limitation of the sim which ultimately defines the cap.

All that "appears" to have happened is a doubling of the design range so I imagine that the rule still applies but now at 200 points. In other words, supplier points that cause an attribute to exceed 200 are wasted.

Because this "cap" is a result of the maximum design value the sim can work with, supplier dp can be used to exceed the lower tier caps and should be effective in terms of improving car performance. 

I also hope that I answered the question well enough.

Or develop up to 200 and use different suppliers to improve another area.

Murk gives you +10 Acc and -6 FE, so the net result is +4 dp
Wonder gives you +10 FE and  -4 Acc so the net result is +6 dp. The downside is you can only achieve 196 Acceleration.
Cosurworthit gives you +5 Tyre Economy and there is no negative. The net result is +5 dp

I'm not recommending any of the above, just demonstrating that you can play games and tweak the balance of the car with different suppliers.