A South Australian Liberal MP is lobbying his own government to do more to alert South Australian motorists who are inadvertently driving unregistered cars.

It comes after a staggering spike in the number of drivers being caught, with many people being stung multiple times.

One of those who made the simple mistake is motorist Peter Coulter, who was fined twice after driving his car for almost a month without knowing it was unregistered.

Liberal MP Nick McBride is lobbying his own government to help unaware drivers who don't know they aren't registered. (9news)

"If I had gone through another three or four cameras where does it end you know ... I could accumulate 10, 15 thousand dollars' worth of fines," Mr Coulter said.

The grandfather from Adelaide's south was caught once by a traffic camera at O'Halloran Hill but didn't know he was breaking the law until being pulled over by police a week later.

"I received no notification from anybody to let me know that was the story," he added.

"They've obviously let the law enforcement know but they can't let me (know), a person that's been driving for 50 years."

The simple mistake cost the 65-year-old close to $1000 and has angered local MP Nick McBride.

"I believe that there are honest people with high integrity that do try to do the right thing and they're being innocently caught out," the MP said.

Mr Coulter received a number of fines because he didn't know he wasn't registered. (9news)

The Liberal MP is demanding his own Government make changes so that reminder texts are automatically sent to motorists when their registration renewals are mailed out.

"There is a registration app out there that allows people to go and check their registrations but a lot of elderly people aren't on to that app ...I think that's where the big loophole here is."

9NEWS recently revealed the number of unregistered motorists being caught has jumped almost 40 percent in the past five years.

Mr Coulter said it highlights the need for change.

"They raised $22 million last year on this exact thing, if that's not revenue raising I don't know what is," he said.