Tesla performs horribly on Laguna Lap, but so do all the American Muscle cars. You basically need a low-weight car with high acceleration to do well.
Other raceway times are also interesting. But that's what I look for in high-performance cars.
That website also has links by car (to see how a particular car does across different racetracks). The Tesla P85D page is here:
http://fastestlaps.com/cars/tesla_model_s_p85d.html
Not very many runs yet, but we can get a glimpse of how it is doing from the four tracks listed.
They take very tight corners. I'd imagine that the turn-intensive tracks would be where these smaller cars would do better. Their acceleration leaves a bit to be desired (but what do you expect for $25k?). 0-60 in 6.3 seconds is still reasonably sporty.
Fiesta is too small for my tastes, but I did go with a Focus (non-ST... just normal stock Focus) for my vehicle. For a manual vehicle, its perfectly fine.
From 4000 through 6500 RPM, you can definitely feel the little engine work. Turbo must kick in or something.
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In any case, its amusing to see "just" the ST models do decently on these tracks. After all, people who actually want performance go for the RS model.