Don,
1 meter of full width (56 inches or 142 cm) will cover the center of two TR7/8 seats but there is not a lot of seam allowance. Please look at my description (link below).
Theo is correct, the material from House of Tartan is not a perfect match (even assuming they are still using my thread counts for the warp and weft which are different). You make the material based on thread counts and it is not an exact science. The mismatch is described in tremendous detail in my google docs article. This is why I chose to wash my fabric. That did take some starch out so it is good to put a backing material on it, but it reduced the dimensions slightly.
My paper has pictures of my seat covers, but I have now updated the google website with a photo of my interior. Note that I have not yet replaced my door cards, but you can see my seats in the car with the red carpet:
https://sites.google.com/site/triumphtartan/
And you can read about the differences in the original and woven materials (and the effect of washing) by reading my document (click on the link at the bottom).
BTW, I have no relations to House of Tartan other than being a customer and I am not in the business of selling fabric - I just did a project and made it available to others. Just trying to be as clear and helpful as possible.
Jim