As I’m driving and pulling up to traffic lights, I usually leave about a full car length between my front end and the rear of the car in front of me. I do this so as not to end up sucking up the exhaust fumes of the car in front of me. It always bugs me a bit when someone pulls alongside me in a different lane and their exhaust pipe seems to be directed toward my car.

It occurred to me, though, that I don’t really know where the intake that brings fresh air into my car is located. I have a 2003 Pontiac Vibe. Where are these intake vents? Are they basically in the same spot for most cars? Any recommendations on not being the recipient of others’ exhaust fumes? I know I can use the recycle mode for the air, but I prefer fresh air as much as possible.

– B. Sull, Waterford, Conn.

I’m not sure if I can be much help reducing the impact of exhaust odors from other vehicles, but we can look at a few related issues with the ventilation system. The heating/ventilation air intake on most vehicles is at the base of the windshield. This location provides optimum airflow to the cabin while the vehicle is moving.

A plastic grille and screen are designed to prevent leaves and debris from entering the plenum, but it’s a good idea to clean this area periodically with a vacuum cleaner. Also, if engine odors should be regularly noticed, one might inspect the rubber seal at the rear hood/cowl intersection, just ahead of the air intake.

Another common odor complaint is mildew, caused by microbial growth on the A/C system’s evaporator and housing. An easy way to minimize mildew buildup is to change the A/C or defrost setting to “vent” during the final mile or so of each use. This stops the formation of condensation and helps dry the condenser’s fins.

Persistent odor problems are best treated professionally by fungicide application to the evaporator and housing. This can be done through strategically drilled holes in the plastic housing or might require complicated disassembly. Minor relief might result from the vehicle owner spraying Ozium or a similar product into the air intake, with the blower set to high.

It’s best to draw in fresh air, rather than recirculate existing cabin air whenever possible. Recirculating air is best done as you mentioned – in heavy traffic, or on very hot days after the A/C system has reduced highly elevated cabin temperature to a moderate level.

The oil filter of my car infuriates me! When I change it, oil runs down the side of the engine, making a mess, and it drips for several days. Why do they design cars like this?

-Jimmy Sauder, Saratoga, Calif.

Jimmy, try this for a sideways-mounted oil filter: After loosening it a quarter turn (to make sure it’s removable), wrap a rubber band around the filter near its closed end and then poke a hole in the filter’s thin metal housing just outboard of the rubber band. The dripping oil can be directed to your drain pan and away from the engine.

Brad Bergholdt is an automotive technology instructor at Evergreen Valley College in San Jose.

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