Where are the "straights" in the diagram? The diagram as posted shows two "concentric" ellipses only.

Anyway, I understand what you mean because we constructed a few of those ovals before.

The inside track:

(Assumed to be the innermost of the oval for this exercise)

Perimmeter, P1 = 400m

P1 = (two semicircles) +2(90) = 400

two semicircles = 400 -180 = 220

one circle = 220 m in circumference

radius, r = 220 / 2pi = 110/pi meters.

The outdside track:

(assumed also to be the outermost of the oval for this exercise.)

radius, R = r +8 = (110/pi0 +8

So,

Perimeter, P2 = (two semicircles) +2(90)

P2 = one circle +180

P2 = 2pi[(110/pi) +8] +180

P2 = 220 +16pi +180

P2 = 400 +16pi meters

So, P2 -P1 = (400 +16pi) -400 = 16pi

Meaning, it takes 16pi meters more to run around the outside track.

In decimals, that is 50.27 meters more.