I own a 1998 CLK 320 Mercedes. It has been sitting in the garage for 8 years. I finally decided to go out and put air in the tires and get it back running. After putting on a new set of tires (original factory set), I put another battery in it. I already had the battery in my garage. All the lights came on and certain things started working. I attempted to start it and got NOTHING. No sound, no attempt to turn over, nothing. I found that odd and began to troubleshoot. I hooked up some jumper cables to the battery that I put in the car and got it to crank but not actually start. Engine is turning over but not actually starting. Any suggestions? Again, it has been merely sitting in the garage for 8 years. Dash shows it has over a quarter tank of gas in it. I am getting spark (pulled a spark plug cable and got fire through it). Any suggestions would be helpful and appreciated.

Thanks in advance,
Bruce