Guys, I've had that problem din sa Innova ko. What I did was get some coal in a fine net and also some baking soda. Mga 2-3 days, nawala yung maisim na amoy. I place it under the driver's seat.
And if you're the adventurous kind, some say sliced onions attract all kinds of bacteria within an enclosed space. You'll know it's working when it suddenly turns dark in color when left usually overnight. I-despose daw agad yun sibuyas at puno yun ng bacteria.
I haven't tried the latter pero if you're really desperate...so I can not guarantee it... baka kasi ang next problem naman eh onion smelling naman rides natin...
Hope this helps...