Back-in-the-day say in the 50's and early 60's gassers were street driven hot rods that were raced at the drag strips on the weekends. They had to be street legal and the class was called Gas Coupes & Sedans. That means NO convertibles or sports cars. They were allowed certain modifications and alterations however they had to run the stock fenders with or without the running boards. They were raised in the front of the car to transfer the weight upon launching the car. They could have headers or exhaust dumps as long as they had mufflers for street driving. I believe they could remove the rear seats, however there must be a passenger seat in the front. Today, the gassers rules are quite different and many people call any car with a raised front end a gasser which is not true and the term "gasser" is used very loosely.