Harald Weinrich - Tempus:
"Wir können auch sagen: daß Vergangenheit im Perfekt nicht als perfectum, sondern als imperfectum erscheint. (Im Imperfekt erscheint Vergangenheit als perfectum.) Dabei ist es nicht zwingend nötig, daß der im Verb ausgedrückte Vorgang selber bis in die Gegenwart weiterläuft."
Oh but I never doubted that some grammarians think that this is the adequate and correct normative description of German tenses.

I know that this view exists, you can even find it in (some) German textbooks and grammars.
(Also I don't think that Weinrich means it this strictly but I couldn't be sure, I've only read a few paragraphs of it on Google books.)
The problem is that I don't think they are right - first and foremost they're oversimplificating, it isn't perfectly correct to claim that Perfekt is for actions still relevant to the present (be they finished or not; like Iberian Spanish pretérito perfecto) while Präteritum is for things which definitely happened in the past (like Spanish tenses imperfecto and indefinido as used in Iberian Spanish).
I can offer some examples from
Andreu Castell, Gramática de la lengua alemana (a quite extensive German grammar written for Spanish learners, and comparing with Spanish tenses as used in Spain).
It says there on page 119 that while in dialogues Perfekt is used (vs. Spanish indefinido), in narratives it is Präteritum, and some sample sentences make quite clear that this is true and that Präteritum is not an option even though the action definitely belongs to the past (quoting now):
- Was hast du nach dem Krieg gemacht?
- Ich habe zuerst zwei Jahre lang als Kellner gearbeitet.
In narrative this clearly would be Präteritum (quoting again):
- Nach dem Krieg arbeitete er zuerst zwei Jahre lang als Kellner.
(Obviously the questions "was ... gemacht" has no place in the narrative except as indirect speech in Konjunktiv, like: "Er fragte, was er nach dem Krieg gemacht habe, und bekam zur Antowort, er habe/hätte ...")
So why not a tempus of "the >distant<past" (that is: Präteritum) is used in German dialogues but one of "past still >present<"? That'd be a clear violation of this rule would one try to stick to it. In Spanish a tempus of the past indeed is used - in the Spanish sentence indefinido is used, even in dialogues.
But of course you also find in this grammar examples where Präteritum is paralleled with Spanish indefinido/imperfecto and Perfekt with Spanish pretérito perfecto.
In Spanish it is very important not to mix up "distant" past and "past which is still present", or more precisely: in Iberian Spanish it is while in American Spanish indefinido may be used in cases when Spaniards would prefer pretérito perfecto.
But in German no such distinction exists: not in the same way, not as sharp as in Iberian Spanish - not even for Northerners I think (of course I will accept if Northerners correct me, this is just my opinion, also by judgement of what was written so far in this thread

).
Romance languages (except for French and northern Italian dialects) still distinguish sharply between both "kinds of" path, and so do Bulgarian and Macedonian in Slavic languages.
But Germanic languages lost this already at Common Germanic stage (which too has been mentioned already), and the similar distinction which developped between Perfekt and Imperfekt in northern Germany is not exactly parallel to the same system in Romance languages.
In Spanish you can indeed set some event apart from the present on
purpose if you use indefinido (instead of pretértio perfecto); but in German this does not work - or only a small minority*) at most would understand such an attempt as such.
*) That is, a small minority even if we're only speaking of Northern Germany. Let alone the rest of the German speaking region.
Also it is important that we don't mix this up with Aspekt (aspect) and Aktionsart (for that see
Wiki; English uses the German term, or also lexical aspect which however may mislead to misinterpret this as aspect) - neither is (technically speaking) relevant here.
There is no parallel for Slavic aspect in any one Romance or Germanic language, aspect also exists independently from time in Slavic (which is exploited extensively by Macedonian and Bulgarian, both of whom have a fully developed aspect system as well as past tenses "of the present" and past tenses "of the past").
Of course people always are mislead to think of Slavic perfective aspect as something similar to Spanish indefinido but I can assure you that this is not the case: you'd get awfully wrong translations if you tried to replace indefinido by perfective aspect. But this post is long enough as it is, and it's anyway leading off-topic (and also there are discussions about this very same topic in Slavic forum already).
And Aktionsart is something different: Aktionsart actually is the closest you probably get to Slavic aspect but still significantly different: it is the difference between "blühen" - durative and "erblühen" - inchoative, etc.; while Slavic perfective aspect in a verb may make clear that an action has been completed while in imperfective aspect it is left unsaid whether an action has been completed or not - completion is irrelevant with imperfective aspect.
But that's only a tiny aspect of Slavic aspect (and excuse the pun), I'm only explaining this to make clear that neither Aktionsart nor aspect are, strictly speaking, to the definition of Präteritum and Perfekt.
So let's put aside that probably no significant percentage of German native speakers (say, more than 10% which I doubt) were using Perfekt and Präteritum consistently in formal written language to mean different things (I don't doubt that a huge percentage of Northerners use both Perfekt and Präteritum - my doubt is about their consistency

), and that even many teachers of German language are incapable of consistantly using any "clear-cut" rules as formulated by grammarians.
(And also we'd better put aside Aspekt and Aktionsart here as this might confuse the situation unnecessarily.)
If we only consider the use of formal standard language by those who have mastered some consistency in distinguishing Perfekt and Präteritum by meaning (and not by style, as is the case in Switzerland, Austria and a good part of Southern Germany at least, and of course I'm talking about formal standard language here) it is still impossible to clearly distinguish Perfekt as the "tense of anything which still has relevance to the present" while Präteritum were the "tense which strictly refers to the past".
As Bernd said:
The choice depends on what you are talking about, whether you are talking about the past event or action of breaking a leg or drilling or whether you are talking about to state of your leg still being in plaster or your teeth still hurting or your teeth being in such a poor state that the dentist had to drill. [/FONT][/COLOR]
This is interesting: so in narrative mood (say, we're interviewing a football player) it would be Präteritum:
(A) "Letzte Saison war ich kaum im Einsatz, da brach ich mir ja schon in der dritten Runde den Fuss, aber diese Saison war richtig gut!"
(I still think that even Northerners might say here "habe ... gebrochen", or if they didn't then "hatte ... gebrochen" which I would consider grammatically incorrect in this case. The action is completed and part of the past either way.)
But Perfekt if referring in some way to the present:
(B) "Diese Saison bin ich ja kaum im Einsatz gewesen, ich habe mir schon in der dritten Runde den Fuss gebrochen." (He's still in plaster, or if he's playing already then still hasn't found his form, so still his broken leg is of relevance to the present.)
Sentence (A) would be incorrect in Spanish if you use pretérito perfecto = more or less Perfekt. If Northerners would consider Präteritum being not only idiomatic but the
only correct choice if you want to give this exact meaning (that is, you need to use Präteritum else people would think you're still in plaster) then I'm inclined to accept that such a rule as suggested by Tifoso could exist; however, I'm doubting this.
In sentence (B) I think you could use both pretérito perfecto = "Perfekt" in Spanish (which however would strongly emphasise that you're still in plaster) and indefinido = to be paralleled with Präteritum (this would emphasise that he's playing again, that the broken leg is past tense for him literally). Again, if it were clear by using of Perfekt alone that you're still in plaster (or at least not fully recovered) I would accept „Tifoso's rule“, but again, I doubt it: I think the use of Perfekt, even for Northerners, wouldn't rule out the option that you've recovered fully already.
(And sorry for only picking a few statements out of the last posts but my answer is too long already as it is.)