For a majority of messages it seems like your product mostly eliminates remaining characters.
I agree that if (1) the receiving device is a smartphone, (2) there is map data available for the used area, and (3) the users knows how to read maps, sending a location link with MMS works well. Or a http- google-maps link with SMS, that gets opened in Google Maps at least in iPhone and Android so works pretty brilliantly too and doesn't cost the price of MMS.
I think we have pretty much proven that landmarks in SMS is a killer feature for consumer vehicle tracking with Tramigo (best selling GPS/GSM tracking device), and in that use simplicity is the key: plain SMS, no need for data connection or anything else than just a plain GSM phone. So we are trying to expand from there.