yes a digital one can be tampered with ..but i dont know whether it can be done in malaysia...i saw it on DW-TV(german TV)..the program called AUTOMOTOR AND SPORTS..
in that they showed that u can actually call ppl to come over and set the mileage to wat ever they want it to..
it just takes the guy a few minutes to do the job..all he needed was a computer and cable connecting to the cars "computer"...
as i said before i am not sure if anyone here has the expertise to do it...