The Society of Motor Manufacturers and Traders said 2.54 million new cars were registered. That's 150,000 fewer than in 2016.
When asked if these figures mean we are heading away from a car-dependent society, Frost told Premier: "I don't think we are because these sales are still quite strong.
"I mean this is the first drop-off in new car sales in six years and still some two and a half million [cars] approximately have been sold.
"I don't think it shows that we are moving away from buying motor cars because this is the first dip in six years and these have been almost a record six years and at some stage it did have to come to an end."
There was also a big decrease in the number of diesel models being bought.
Speaking on these figures, Steve Frost said: "A lot of later diesels are reasonably clean vehicles, the ones the Government are trying to get off the road are the older ones which don't comply to the latest euro emissions - they can be quite dirty diesels."
He said he'd noticed a change towards more people wanting to buy cars that are better for the environment.
He added: : "There has been a move for people to buy some of the nearly-new vehicles. These hybrid electric cars are quite expensive pieces of kit to buy so if you can buy those if they're six months to 12 months to 14 months old and lower mileage rather than buying brand new, you can get a huge, huge saving.
"Hybrids have seen a great increase. I think last year hybrid and electric sales were up almost 35 percent year on year from 2016 so there's a definite movement towards that area."
Listen to the full interview with Steve Frost, owner of Priory Automotive, with Premier's Cara Bentley: