+1. Less rotational inertia to spin up. That should show up on the dyno as well (less driveline loss), but I haven’t tried that yet.

 

It sounds a bit strange but the less your car weights, the more you lose performances with the increase of the weight.

 

I too drive differently with a passenger, so haven't noticed a difference with the F-Type. I have; however, noticed that my Miata with a passenger (and a case of wine in the trunk), needs to have a little speed at the bottom to make it up my driveway.

I went for a ride-along with a seasoned Miata time trial driver and HPDE instructor. He had an electronic timer in his car and I saw him doing very consistent laps (~2:03) during the session. I asked him afterwards how much the 200 pounds of ballast cost him, and he said 3 seconds per lap. That's at Sonoma, on the full course, although I can't remember the T7 configuration. I think it was traditional, but am not certain.

 

The F-Type has better power to weight ratio than a Miata, so you will notice an increase in weight a lot more than the F-Type.

 

I own both an F-Type and a Miata and I find that I weigh exactly the same in both. Weird!

 

I took a passenger for a couple of runs up the track when I was doing drag racing late last year. With him in the car there was a difference of a couple of mph and around .3 secs difference in the standing quarter as well.

 

That's exactly the point I was trying to make, but my communication skills are lacking sometimes. Haven't noticed anything in the F-Type even under moderately hard driving, but for a grocery run in the Miata, I can tell I'm encumbered.

Sure, but percentage-wise, I'm much more svelte in the F-Type.