You have to possibilities:
1) Set up a redirect on you Port 80 VirtualHost that ignores the subfolder autos:
RewriteEngine On
RedirectMatch 301 ^((?!(autos)).)*$ https://your-domain.ain/
Note: This does not keep the path in the URL. So http://your-domain.ain/path/to/sth will be redirected to https://your-domain.ain/.
2) IMO the better Solution would be to create a own VirtualHost for the subfolder autos.
<VirtualHost *:80>
ServerName autos.yourdomain.ain
DocumentRoot /var/www/autos
ServerAdmin name@domain.com
# Write a seperate log per Virtualhost
CustomLog /var/log/apache2/autos.access_log combined
ErrorLog /var/log/apache2/autos.error_log
# Maybe you want to put some restrictions on the directory
<Directory /var/www/autos>
Options -Indexes +FollowSymLinks + Includes
AllowOverride All
# Restrict Access to certain IP's (change IP to a real IP or comment out)
Order Deny,Allow
Deny from All
Allow from 127.0.0.1 IP IP IP
Satisfy ALL
</Directory>
</VirtualHost>
You can find further information on Apache VirtualHosts and some examples in the Apache Manual.
EDIT: For the seperate VHOST you'll need to use NameVirtualHost.
Make sure you have the following Entries in your Apache conf:
NameVirtualHost *:80
Listen 80
NameVirtualHost *:443
Listen 443