The two sentences grammatically are correct in MSA it's called dual(المُثَنَّى)
the first sentence nominative(الرَّفع )
علامة رفع المثنى الالف والنون
Mark dual nominative الالف and النون
the second sentence accusative(ألنَّصْب)
Mark dual accusative الياء and النون
علامة نصب المثنى الياء والنون
but if you want say that in Shami dialect you sayسيارتين and in egyptian dialect you say عربيتين