Hey, I want the second options. get_post_meta()

If I am understanding your question correctly, you have a post meta which will return you your vehicle type and based on this you wish to create something like:

$vehicle_type – My $vehicle type

If you are not venturing into categorization of vehicle after vehicle type then the below mentioned code should work fine.

foreach ($engine as $key => $val) {
    echo $val . ' - My ' . $val . ', ';
}

If you want a structure like

car – My Batmobile, boat – My nautilus, bike – My hoverbike

and your are sure of what value to put based on vehicle type, then this code should work

foreach ($engine as $key => $val) {
    if ($val == 'car') {
        echo $val . ' - My batmobile, ';
    }
    if ($val == 'boat') {
        echo $val . ' - My nautilus, ';
    }
    if ($val == 'bike') {
        echo $val . ' - My hoverbike';
    }

}