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ev99, I know a guy who had similar high Wh/mi on his BMW Z3. The Warp motors were originally developed for drag racing and the brushes that were usually installed were made of an H49 compound for HIGH CURRENT applications. Your Cobra is so light I doubt it's capable of drawing the current these brushes require.
When Tim switched to Helwig's "Redtop" brushes during a motor rework, he experienced a 15% improvement in Wh/mi. Here's his Blog:
evz3.blogspot.com/search/label/Brushes
The Redtop brush is a split or double brush made with a harder H60 compound. The split brush design maintains better contact with the commutator lowering resistance and consequently energy use & commutator temperature.
Tim's results were confirmed in testing by EVTV's Jack Rickard:
blog.evtv.me/2012/05/escaladus-interruptus-and-the-catellier-effect
You can tell which brushes are in your motor by looking at the number of wires to each brush - the Redtops have two wires (one for each half of the brush) while the stock H49 only has one. Jack has the brushes for sale on his site or you can get them from Warp motors. They're not cheap at ~$200/set, but they should save you money in the long run in energy (fuel) cost and, being harder, last longer.
It's more work but if you want to occasionally race your Cobra, you could switch to narrower Bridgestone "Ecopia", or a similar LLR tire and the Helwig Redtop for daily use; then swap to your current wide tires for shows and the H49 brushes for the occasional race.
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