Aston Martin built 325 Vanquish Zagatos – 99 Coupés, 99 Volantes, 99 Shooting Brakes and just 28 Speedsters. Currently, there are 12 of the ultra-exclusive Anglo-Italian V12 Grand Tourers listed for sale on Classic Driver. So, which will it be? We’d take a Speedster, to make the most of the summer…