My 735i is not re-starting after being driven for more than 20 minutes. Once the engine is turned off, I cannot get it to start for 30 to 45 minutes. When I try to turn it over it doesn't even crank, then after I wait vroom, it's going again, till I turn it off the next time. The battery is brand new and meters fine. What should I check and/or do?

Have you had the starter checked?

If you check your starter and find it is OK, then look at the ground side of your system. The connections make look good but have a high resistance. Once they have current flow on them it makes the problems worse, finally the circuit breaks down not allowing any current flow until it cools off. Take loose and clean the connection points well with a wire brush or something of that nature. Hope this helps.