Amazon has discounted several vehicle sets from the LEGO City line. Any of these sets would make a nice addition to your collection.
If you don’t own LEGO City Flatbed Truck (60017) yet, it’s available for $13. That’s a big discount of 33% off. It’s a 212 piece set that comes with 2 vehicles and 2 minifigures. LEGO City Camper Van (60057) & LEGO City Tow Truck (60056) are also on sale for $16 each which is a 20% off discount. If you want to go bigger, LEGO City Auto Transporter (60060) is on sale for $24.