PA-28 Cherokee/Archer/Dakota/Pillan/Warrior
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Flight Instructor; Flight Crew Commercial
Flight Crew Last 90 Days 82; Flight Crew Total 518; Flight Crew Type 53
Aircraft Equipment Problem Critical
Air Traffic Control Provided Assistance; Flight Crew Returned To Departure Airport; Flight Crew Landed As Precaution
Aircraft
I departed ZZZ just after XA:00 local on a takeoff and landing training flight with an initial student pilot. We departed for ZZZ1 for work in the traffic pattern. As we climbed and approached our cruising altitude of 3;500 feet MSL; we both noticed the engine miss occasionally on a few strokes every minute or so. We both adjusted mixture to see if that smoothed it out without success. Then as we leveled off; I began to smell a gas-like odor. I continued to scan instruments to have an indication of a malfunction. As I was doing this; my low-time student pilot commented that he smelled a gas odor without me soliciting whether he smelled anything. I immediately asked him to turn 180 degrees back towards ZZZ and we would return to the field. As he did; I entered ZZZ into the GPS; pulled up ATIS; and then contacted the Tower roughly 15 miles northeast of the field. I advised the Tower that we had mild and occasional engine roughness and were returning out of precaution. I also let the Controller know that we had encountered an unusual odor. He asked if we needed any assistance and I replied; 'Not at this time.' Shortly thereafter he asked for souls onboard and fuel remaining and offered us a straight in approach to [Runway] XXL. I accepted and we flew a high final and then slipped the aircraft in just in case we lost power and needed to glide. We landed uneventfully and taxied to the ramp.I believe the quick decision was good to return to the aircraft quickly and also to advise ATC of our situation. This allowed them to help us expedite our arrival and understand any challenges that may have suddenly arisen should things have deteriorated. It was a very good learning experience for my student who now has an understanding for how to handle a challenging situation in the air.
PA-28 instructor pilot reported engine was missing and smelled of gas during climbout.  They decided to return to the departure airport and landed safely.