My thinking on this hasn't change much over the years.
And that is, if you genuinely don't need a back seat, never buy a car that has the built in compromise of being designed around a chassis that must accommodate one. The reason is, you'll never get optimum performance with that baggage in tow.
It is rather like choosing a mate. If you don't plan on having kids, please don't choose a wife based upon the criteria of her motherly capabilities or child rearing/raising potential. If you do, you are bound to look at others in your same no-offspring situation with envy.
2008 Interlagos Blue E93 M3 - M-DCT
2011 Salsa Red Jetta TDI Sportwagen - DSG