For those with little one's , there is a mob in melbourne that make a harness that goes with lap belts, you still need a anchor bolt but this harness is much safer than a lap belt on its own , can be used with booster seat or without, the lap belt goes through the harness, and harness bolts to anchor up top , click on link below.
regards shaz
http://www.hemco.com.au/seatbelts.html

I guess I'm showing my age, as my youngsters are 22 and 17, but those harnesses used to be commonly available at Repco, Auto One, etc.

I suppose there aren't many cars that have just lap belts anymore.  

Hi Sharon,
We just bought the foam portable seat for Zac and they run the same set up with a buckle for the retractable belt to become one strap across the waiste as a lap.

Hooroo

Luke

I just tellem to hang on tight!
Popa's Driven!

http://www.karlisles.com.au/

Just off Botany Road Botany NSW, supplies all that stuff, seats, seat belts seats in vans etc etc.

Tell Lisle (Karlisle) Garrett sent you.

Got 2 baby seats and harnesses in my XT with anchor points etc.