Carl Williams, the proprietor of Carl Williams Auto Sales, estimates that with extensive television advertising, car sales over the next several years could be increasing at the rate of$4$e$^0\mathrm{.}3$tthousand cars$/$year$,$ t years from now, instead of at the current rate of$4+0\mathrm{.}5$t$^3/2$thousand cars$/$year$,$ t years from now. Find how many more cars Carl expects to sell over the next $7$ years by implementing his advertising plans. $($Round your answer to the nearest whole number.$)$cars