just don't drive in the express lane then :P 我开车开得很慢。

我车开地慢；我开车慢；我慢慢得开车 。 Wǒ chē kāi de màn, wǒ kāichē màn, wǒ mànman de kāichē And if you want add “very” in the sentence you can say these: 我开车很慢；我车开很慢。 Wǒ kāichē hěn màn, wǒ chē kāi hěn màn. Please notice that there is not "de" anymore.

eh,remember a most rule of chinese: only say the useful characters in a sentence. 我开车慢(wo kai che man)is enough to express your opinion,so "de" can be cut away. :)

wo kaiche man 我开车慢

You can say straightly: "Wǒ kāi de hěnmàn." You don't have to say: "kāichē", becouse when you say "kāi" the people will see that means "kāichē". This scentence's grammer is about the "complement of state", usually,the structure is Verb + de(得)+adjective. The word after "de(得)" is a comlement which expresses the state. "hěnmàn"is a comlement here and it expresses the state of "kāi". If you have to use "kāichē", you should say:"Wǒ kāichē kāi de hěnmàn." Example sentence: "Tā pǎo de hěnkuài. (he runed very fast.)"; or you can say:"Tā pǎobù pǎo de hěnkuài."