I wouldn't be so sure of that either Erkki: it is true that the USSR got most of its trucks from the US? but how do we know they wouldn't have been able to produce more of them if Lend-Lease didn't happen? I think that "What would have happened if Germany had been fighting the USSR alone" is firmly in the realm of idle speculation.
They would have certainly been able to produce more of them. The problem is that this would have taken factories and production time/resources away from building tanks, which is why using tank and aircraft production alone is inadequate to illustrate just how sorely (or not) the Germans were overmatched industrially.
Which I would also assert they were, but not to the point of being a "military and economic powerhouse." The Soviets went immediately to a total war footing industrially and societally; the Germans did not do this until 1943, a year later. The Soviets did have a superiority in heavy industry (imbalances in their economy being irrelevant to the discussion), though I would suggest that German industry was more efficient. Finally, German industry was under the guns and bombs of Allied air wings, whereas Soviets, after the early dislocation in 1942, steadily reaped the benefits of moving significant portions of their heavy industry out of the range of German bombers.
As for winning without Lend-Lease, the Soviets "won" in 1942 insofar as their survival was concerned, with the German failure to take the critical rail hub that was Moscow (even after the mud hardened, they still had another shot, and they failed again); the question was how much victory would cost. You might actually see a status quo ante bellum, or a pre-1939 Soviet border where they cede their Molotov-Ribbentrop gains, but the USSR would survive.
Also, Case White was also the code-name for the Invasion of Poland. The Germans were almost as fond of their color plans as the Americans, but unlike the Americans, tended to recycle a few colors over and over again (like how Green represented first the invasion of Czechoslovakia, and later both the invasions of Ireland or Switzerland).