Smell of natural gas

I have a 2005 Audi Allroad and sometimes when I get in the car after work there is a strong natural gas smell in the car which goes away after I drive away. I park in an underground garage so for a while I thought it was the garage but I have smelled it on the week ends now too occasionally at home parked in the drive way. I also have a freakishly accurate sence of smell and have often detected smells others could not. I am sure it is not a gasoline smell but a natural gas like smell. Any ideas what this could be?

Idon’t know but natural gas is oderless. They put a substance in it so that it can be detected if there is a leak. It might be fumes coming from the gasoline but otherwise don’t have a clue.

Sometimes a car that’s not running right will allow unburnt hydrocarbons and volatiles to pass out the exhaust. On warmup too, unburnt fuel can be noticed until the car’s systems are warmed up enough to go into “closed loop”. This could be what you smell. You may also have gotten a batch of high-sulfur gas, which can cause noticeable smells. A battery that’s overcharging due to a problem with your vehicle’s charging system can also have a sulfur smell to it.

Another long shot is that gear oil contains a lot of sulfur compounds–you could have some seepage from a differential or transfer case, if they use this type of oil, which may be contacting something hot, amplifying the smell.

Also, check your coolant. Today’s long life coolants have different smells than the sickly sweet smell of classic ethylene glycol. The stuff in my wife’s Explorer smells more like acetone.

The chemical that gives natural gas it’s smell is usually mercaptan. It contains sulphur and has the characteristic odor that you likely smell. You could check with the home natural gas seller in your area to see what they put in just to make sure it is mercaptan. Knowing the chemical you smell might help us figure out what you smell. Also, how many miles an your Audi?

Start the engine when cold, and while it’s idling stand at the rear of the vehicle to see if you can determine of this odor is coming out of the exhaust pipe. If it is the odor is from the sulfur in the gasoline.

As mentioned, mercaptan is added to natural gas to give a sulfur odor or a rotten egg odor so if there’s leak it can be detected.