There's a similar system available in the UK:
http://www.traceamobile.com/

Cost is from £5.month (5 phones) or £50/year (10 phones) with bundled search credits which go from 50p down to 20p a search.

They used to claim that tracked phones have an SMS regulalry sent to them but there is no mention of this on the site!

Either way it would be a neat way to track somebody's car - just wire a pay-as-you-go phone under their dashboard and remove the speaker and ringer.

Gareth