If you’re going to be driving in Maryland be careful to not exceed posted speed limits. If you are CWP holder Md has no reciprocity with your home state. Concealed carry is prohibited unless you have a permit from Md itself. No loaded readily accessible handguns may be carried in any vehicle. Keep all radar detectors out of your vehicle. If you get pulled over and they see one you will get a ticket.
They are very expensive. Make sure your car rental docs are in complete order. Md is NOT visitor-friendly.
OTOH Pennsylvania has pretty much given up on speed enforcement on the Interstates.
Downside is that I-81 has become a deathtrap. Fatals almost every day.
Maryland gun laws, like New Jersey laws, are designed to trap law abiding gun owners who make technical errors. If you do not have a Maryland concealed carry permit and are make ANY stops in Maryland DO NOT take any handgun, even if it is unloaded and locked in the trunk or a case. The federal law travel exception only applies if you’re are passing through the state.
Radar detectors are illegal in Virginia but not Maryland.