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How Much Padding Should I Expect From My Fibreglass Bucket Seat?

Your questions, seat padding

"How much padding do the seats really have?" is one of the questions we are asked most. It matters, because the thickness of the base cushion changes both how comfortable a seat is and how high it puts you in the car.

To give a straight answer, we lined up one fibreglass bucket seat from each of five brands we sell, Sparco, OMP, Mirco, Corbeau and Cobra, and measured the main base cushion on each in our showroom. Here is what we found, and what it means for choosing a seat.

  • We measured one fibreglass seat per brand in our showroom
  • Sparco: about 40mm of base cushion, the thinnest fixed cushion we measured
  • OMP: about 55mm, and firm
  • Mirco: about 60mm; Corbeau: about 65mm
  • Cobra PRO-FIT: about 35mm, 60mm or 75mm, depending on the cushion fitted
  • Thinner padding puts you lower; thicker padding is more comfortable over long stints
Five black fibreglass bucket seats from Cobra, Corbeau, OMP, Sparco and Mirco lined up on the GSM Performance showroom floor for a padding comparison
The five seats we measured, side by side in our showroom: Cobra, Corbeau, OMP WRC-R, Sparco Evo and Mirco RS1.

Why base cushion thickness matters

The base cushion is the padding you sit on, and its thickness does two jobs at once.

A thinner cushion puts you lower. For a tall driver, or a car with a low roof such as a classic sports car or a kit car, a few millimetres can decide whether your helmet clears the roof. Sitting lower also brings your weight down in the car.

A thicker cushion is more comfortable. More foam takes the edge off bumps and vibration, and reduces fatigue over long drives, regular track days or endurance stints. For a car used on the road as well as the track, that counts for a lot.

The cushion is only one part of your final seat height; the frame, runners and mounts all add to it. Our guide to seat height and fitment covers the rest.

What we measured, brand by brand

These are approximate figures from one representative seat per brand, measured in our showroom. Different models within a brand can differ, so treat them as a guide to each brand’s approach.

Brand (seat measured)Base cushionCharacter
Sparco (Evo)About 40mmThin, sits low
OMP (WRC-R)About 55mmThin and firm
Mirco (RS1)About 60mmThicker, softer
CorbeauAbout 65mmGenerous, road and track
Cobra PRO-FITAbout 35mm, 60mm or 75mmChoose the cushion

Sparco, about 40mm. The thinnest fixed cushion we measured. That makes Sparco a good starting point for a tall driver or a car with little headroom, where every bit of height counts, and for track focused builds.

OMP, about 55mm. Also on the thin side, with a firm feel that keeps you connected to the car. A good match for committed track day driving.

Mirco, about 60mm. Thicker and softer, for drivers who want more comfort over longer stints without giving up the deep, supportive shape of a bucket.

Corbeau, about 65mm. The most generous fixed cushion we measured. Supportive without being hard, which suits a dual purpose car that has to be comfortable on the road and hold you on the circuit.

Cobra, about 35mm, 60mm or 75mm. Cobra do things differently. Their PRO-FIT seats take interchangeable cushions, so you choose the base cushion to suit: a low one of about 35mm for headroom, a medium of about 60mm, or a high one of about 75mm for comfort and thigh support. Cobra make matching leg cushions too.

If you drop to the low base cushion, Cobra's low leg cushion is worth pairing with it, so the front of the seat comes down too and your thighs do not take all the pressure. The PRO-FIT cushions fit the Imola, Suzuka, Evolution and Sebring, with separate parts for GT width shells.

A row of black fibreglass bucket seats from Sparco, Cobra, OMP, Corbeau and Mirco on the showroom floor, seen from a low angle
The same five seats from a low angle, showing the different cushion shapes.

Choosing the right cushion for you

  • For the lowest seating position: Sparco, or a Cobra PRO-FIT seat with the low base cushion. These suit tall drivers and cars with tight headroom.
  • For comfort over long stints: Mirco or Corbeau, with their thicker cushions, or a Cobra with the high cushion.
  • For a firm, connected feel on track: OMP.
  • If the car is shared or you are not sure: Cobra’s PRO-FIT system lets you change the cushion later.

Garreth’s advice is to think about how the car is really used. A seat that feels right for ten minutes in the showroom can feel very different after two hours, and the reverse is true of a thin race cushion on a long drive. Send us your height, the car and what you use it for, and we will help you pick.

Of the fixed cushions we measured, Sparco’s was thinnest at about 40mm. A Cobra PRO-FIT seat with its low base cushion was about 35mm.

The thicker cushions we measured were Corbeau at about 65mm and Mirco at about 60mm, or a Cobra with the high cushion at about 75mm.

Yes. Cobra’s PRO-FIT seats take interchangeable base and leg cushions in different heights.

Yes. Less padding under you lowers your seated height, which helps with headroom and helmet clearance.

No. They come from one representative seat per brand, so treat them as a guide.

💬
The trade-offHeadroom or comfort

Thin padding sits you lower; thick padding keeps you fresh. Cobra's PRO-FIT lets you choose.

Need a personal recommendation?

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