If your cars object is a data frame, there is no need to run it through the tibble() function. I get an error when I try that
Error: Column `cars` must be a 1d atomic vector or a list
Also, filter can take bare column names.
library(dplyr)
#>
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#>
#> filter, lag
#> The following objects are masked from 'package:base':
#>
#> intersect, setdiff, setequal, union
data(cars)
head(cars)
#> speed dist
#> 1 4 2
#> 2 4 10
#> 3 7 4
#> 4 7 22
#> 5 8 16
#> 6 9 10
carsx <- filter(cars,speed == 20)
range(carsx$speed)
#> [1] 20 20
Created on 2019-05-14 by the reprex package (v0.2.1)