Yes, i've just had a look in an old nuvi 300 which has similar menu and maintenance pages to the earlier SP and nothing there either. As to modding the SPc510 firmware to enable a trip/track log, even if possible it would involve far too much work by a navigation software expert to make it viable in my [non-expert] opinion.

Your zumo would be better suited to a bit of 'rough & tumble' in the wilds of Africa than a girly nuvi 2445 imo also.