it doesn't honestly help anything,myth busters tested this theory over and over and it actually made some trucks use more gas,a lot of people do it though thinking it helps,but it doesn't even i have tried it and it didn't help any at all,good luck.
it doesn't honestly help anything,myth busters tested this theory over and over and it actually made some trucks use more gas,a lot of people do it though thinking it helps,but it doesn't even i have tried it and it didn't help any at all,good luck.